With respect to God's action in the sacraments, sign and reality correspond directly. The sacraments are so adapted by God as to portray in their outward form that which is conferred upon men by him in the spiritual realm. With respect to the manward side, the sacraments serve as a means by which we confess our faith before men.
The benefits of the redemption secured by Christ are communicated to the believer through this union. But the union of believers with their Head has special reference to the human nature of Christ. Christ's human nature was the means by which sacrifice was made, sin was punished and righteousness was secured. Christ accomplishes His redemptive work by uniting Himself to His people. Calvin puts it thus: "...becoming Son of man with us, he has made us sons of God with him; that by his descent to earth, he has prepared an ascent to heaven for us; that by taking on our mortality, he has conferred his immortality upon us..." Hence, as Calvin says, believers enjoy a "holy brotherhood" with Christ in His incarnation. [5 ] The Holy Spirit effects, so to speak, an "exchange of properties between the Son of God and mankind."
As union with Christ depends solely on the work of the Spirit, the sacraments, which are seals of this union, are efficacious only through the sovereign power of the Spirit. Grace is not inseparable from the celebration of the sacraments themselves. Grace is conferred only when God pleases to bestow grace through the sacrament. The sacraments, according to Calvin, are not to be regarded as automatic dispensers of grace.
How then is the presence of Christ to be understood? Wallace has observed that Calvin achieved clarity in his treatment of the sacrament not by thinking through it but by thinking around it.  Calvin acknowledged that at the heart of the sacrament there is a miracle and a profound mystery. He never sought to reduce the mystery to reason but rather preserved the mysterious element. We cannot, then, demand a clarity of language such as is set forth by the proponents of opposing theories. Calvin's opponents, Westphal and Tileman Heshusius, accused him of ambiguity and subtlety. They sought a sacramental theory in concrete language but did not find it in Calvin. We must, therefore, in examining Calvin's teaching, appreciate his method and not seek more than a "stammering" definition. Here we move in the realm of mystery.
Calvin avoided the language of "physicality" employed by the Lutherans. Christ's body and blood were to be "understood in terms of Christ's act of reconciliation, not in themselves." Although the believer, through the Supper, possesses a true communion with Christ's natural body and blood, it is not in terms of substantiality but rather in terms of the spiritual, redemptive benefits inherent in the resurrected and ascended body of Christ. Hence, for Calvin, a local presence is not necessary. The body of Christ remains in heaven. There is no "descent" of Christ to earth. "Flesh must therefore be flesh; spirit, spirit -- each thing in the state and condition wherein God created it. But such is the condition of flesh that it must subsist in one definite place, with its own size and form."  The human properties of Christ's body are not impaired. Moreover the elements of the Supper retain their full, substantial identity as bread and wine.
There is however a descent of the Holy Spirit who constitutes the connection between the risen Christ and the souls of believers. "No extent of space interferes with the boundless energy of the Spirit, which transfuses life into us from the flesh of Christ." "It is certainly a proof of truly divine and incomprehensible power that how remote so ever He may be from us, He infuses life from the substance of His flesh and blood into our souls so that no distance of place can impede the union of head and members."  The manner in which Christ's flesh is eaten is spiritual. The Holy Spirit communicates the life-giving benefits of Christ's natural body to us.
Although, on one hand, Calvin denies the descent of Christ's body to us (absentia localis), he paradoxically speaks of such a descent by the Holy Spirit as the source of real presence (praesentia realis) in the Supper. Calvin would only allow the word "real" (reali) to be used if it meant that which was not fallacious and imaginary or the opposite of that which was deceptive and illusory. On the whole he preferred the word "true" (vero) to describe Christ's presence. In normal speech "real" connotes something that is existent, objective, and in the external order. When used with reference to the Supper, "real presence" implies "local presence," and, of course, this is denied by Calvin. So then, Calvin would allow the phrase praesentia realis only if "real" was used for "true" as is sometimes the case in common or vulgar parlance. As for the mode of "descent" (modum descensus) Calvin maintains that it is the Holy Spirit who descends but not alone. Christ "descends" by His Spirit. But again Calvin employs paradoxical language when he maintains that the manner of descent is that "by which he lifts us up to himself. There is, so to speak, a simultaneous descent and ascent. What is in view, here, is sacramental "proximity" effected by the Spirit upon the ground of the mystical union of Christ and His people.
Calvin maintains that the sacrament's effect is more than a mere stimulation of the intellect, imagination, and emotions at the sight of the portrayal of the spectacle of the Cross. It is this and more. "In participation in the Supper faith connects itself with something outside of itself and other than a mere idea, and, in so doing, effects in the spiritual realm a real communication between itself and the earthly reality such as that figured in the act of eating the bread." Calvin distinguishes between eating and believing. Faith or belief receives Christ and the promises, but eating implies more. Eating is the result or consequence of faith.  The spiritual transaction which occurs possesses the nature of nourishment or vivication. "...the flesh of Christ is eaten by believing because it is made ours by faith..." Hence, the eating (nourishment) follows from believing (appropriation). Or, in other words, faith is a vessel that receives something from outside -- the benefits of Christ's flesh and blood which nourish the believer and impart to him eternal life.
Calvin derives his doctrine of the Supper from the accounts of the eucharistic institution in the Gospels as well as from the Pauline words of institution. But the most significant passage for Calvin is John 6:26-65 (The Bread of Life Discourse). He acknowledges that this passage does not have primary reference to the eucharist as some interpreters have understood it.  However, he also recognizes that the passage here refers to the life-giving properties with which Christ's body is imbued. Commenting on John 6:51 he says, "As this secret power to bestow life, of which he has spoken, might be referred to his Divine essence, he now comes down to the second step, and shows that this life is placed in his flesh, that it may be drawn out of it." Calvin later speaks of the supper as being the "seal" of the doctrine taught in this passage. Calvin recognizes that this vivifying power of the body of Christ, received by faith, is the power communicated in the Supper itself. But further than this he cannot go. "Now, if anyone should ask me how this takes place, I shall not be ashamed to confess that it is a secret too lofty for either my mind to comprehend or my words to declare. And to speak more plainly, I rather experience than understand it."
Yet theirs was indeed Calvinism with a difference, for Puritan definitions of sacramental benefits represented a departure in tone and emphasis from Calvin. Because they elaborated the dichotomy between flesh and spirit, especially in terms of psychological interiority, the Puritans tended to rely on subjective explanations of sacramental efficacy.
A certain imprecision entered into Puritan sacramental discourses. The presence of Christ was interpreted in a thoroughly subjectivistic manner. "It will not do to categorize these ministers as either Calvinists or Zwinglians: in the doctrine of the presence, the issues were too blurred."  Some ministers, however, retained Calvin's understanding of the spiritual presence. Richard Vines and John Owen even went beyond Calvin in stressing the uniqueness of the sacramental presence. In codifying the Lord's Supper, the Westminster Assembly approximated Calvin's doctrine. However, the work of the Spirit in the sacrament is not mentioned, and instrumental language, as in the Belgic Confession, is not employed (e.g. faith is the hand and mouth of the soul etc.).
Seventeenth century Reformed dogmatics set forth the axiom, "the finite cannot contain the infinite" (Finitum non capax infiniti). As applied to Christology, this principle led to a separation between the human and divine natures of Christ. There could be no confusion of his natures. Francis Turretin developed this principle more clearly in his Institutio Theologicae Elencticae (1679-1685). Princeton Seminary transplanted Turretin's continental tradition when it adopted his Institutio as its theological textbook. Charles Hodge used this text to instruct large numbers of Presbyterian ministers in the middle decades of the nineteenth century. Robert Lewis Dabney also employed Institutio at Union Theological Seminary at Richmond. In time, the Reformed rationalism and sacramental theology of Turretin permeated the ranks of much of American Presbyterianism. However, at Columbia Theological Seminary in South Carolina, the Professor of Theology, James Henley Thornwell, and the Professor of Church History and Polity, John B. Adger, employed Calvin's Institutes as the text for theology and ecclesiology with the result that many Southern ministers were Calvinistic in their sacramental theology.
These two strains of Reformed sacramental theology came into conflict when John Nevin published his controversial The Mystical Presence in June 1846. Nevin, professor of theology of the seminary of the German Reformed Church at Mercersburg, Pennsylvania, had been much influenced by German philosophy, especially that of Hegel, and also by the High Church movement of the nineteenth century. Nevin had been a student of Charles Hodge at Princeton but later repudiated Hodge's sacramental theology. He sought to demonstrate the historical decline of the doctrine of the Supper that had occurred in the Reformed churches and also to revive Calvin's doctrine which had been codified in the Belgic Confession, one of the symbols of the German Reformed Church. Hodge responded to Nevin's volume in 1848 in a long article in the Princeton Review. First, he tried to demonstrate that the symbols of the Reformed churches did not contain the high doctrine of the Supper that was set forth by Calvin in the Institutes. Next, he made the incredible assertion that Calvin's true opinion, pertaining to the nature of Christ's presence in the Supper, was to be found not in the Institutes but in the Consensus Tigurinus, a symbol that was framed for the purpose of uniting the Swiss churches. He implied that the view set forth in the Institutes was intended by Calvin to be a mediating position in order to conciliate the Lutherans. Finally, he refuted Nevin's theory of the Supper with its Hegelian overtones.
Hodge takes exception to Calvin's view that, by virtue of Christ's divine nature, his human nature possessed a certain vivifying efficacy of life-giving power that was communicated to the believer in the Supper. The influence of Turretin is here seen in Hodge's Christology. Christ is present in the Supper, according to Hodge, only in that the benefits of his body and blood, namely forgiveness and imputed righteousness, are applied to believing recipients. Hence, through the Supper, the believer is strengthened and confirmed in faith. It is apparent that the controlling motif of Hodge's theology, federal headship and imputation, is at work in his conception of the sacrament.
Dabney's view of the Supper is identical to that of Hodge. He says of Calvin's view, "it is not only incomprehensible, but impossible."  He also maintained that the Westminster Assembly modified Calvin's view so as to remove "all that was untenable and unscriptural in it." 
In 1876, John Adger rose to Calvin's defense in an article in the Southern Presbyterian Review. Adger points out that Hodge had caricatured Calvin's view. Nowhere did Calvin ever speak of a vivifying efficacy "emanating" from Christ's glorified body. The life-giving benefits of Christ's flesh are communicated to the believer by the work of the Holy Spirit. Adger goes on to show that Calvin's teaching was incorporated into all of the Reformed symbols. Moreover, he demonstrates that Hodge mistranslated the Latin versions of the Consensus Tigurinus. Thus, Adger demonstrated that Hodge's view was out of accord with the prevailing view held in the Reformed churches from the time of Calvin.
 Ronald S. Wallace, Calvin's Doctrine of the Word and Sacrament, (Edinbrugh: Oliver and Boyd, 1953), p. 143.
 Inst. IV 17.1.
 Inst. IV 17.2.
 Wallace, Word and Sacrament, p. 148. Cf. Inst. 12.2.
 Ibid., p. 148.
 Inst. IV 14.7.
 Inst. IV 17.7. Cf. 17.3 0.
 Wallace, Word and Sacrament, p. 219.
 Cf. "Second Defense of the Sacraments" and "True Partaking of the Flesh and Blood of Christ" in Tracts and Treatises, Vol. II.
 G.C. Berkouser, The Sacraments (Grand Rapids: William B. Eerdmans Publishing Comapny, 1969), p. 229.
 Inst. IV 17.24.
 Corpus Reformatorum, 37: 48. Cited by Wallace, p. 206.
 Ibid., Cited by Wallace, p. 207.
 Joseph N. Tylenda, "Calvin and Christ's Presence in the Supper-True or Real", Scottish Journal of Theology, 27 (1974): pp. 65-75.
 Inst. IV 17.16.
 Wallace, Word and Sacrament, p. 212.
 Corpus Reformatorum, 9:75 C. Wallace p. 212.
 Inst. IV 17.5.
 Inst. IV 17.4.
 Commentary on the Gospel According to John, ad loc.
 Ibid., on 6:56.
 Inst. IV 17.32.
 E. Brooks Holifield, The Covenant Sealed: The Development of Puritan Sacramental Theology in Old and New England, 1570-1720, (New Haven and London: Yale University Press, 1974), p. 53.
 Ibid., p. 59.
 Ibid., pp. 126-131.
 E. Brooks Holifield, "Mercersberg, Princeton, and the South: The Sacramental Controversy in the Nineteenth Century", Journal of the Presbyterian Historical Society, 54 (1976), p. 245.
 Charles Hodge, "Doctrine of the Reformed Church on the Lord's Supper", The Biblical Repertory and the Princeton Review, 20 (April 1848): 227-77.
 Robert L. Dabney, Lectures in Systematic Theology, (1878, reprinted: Grand Rapids: Zondervan Publishing House, 1972), p. 811.
 John Adger, "Calvin Defended Against Drs. Cunningham and Hodge", The Southern Presbyterian Review, 27 (1876), pp. 133-166.