In a letter to Philip Melanchthon from August 1554, 1 Calvin writes in part to show whether and how far he is in agreement with Luther’s sacramentology.
Clamavit tota vita Lutherus, non alia de re se contendere, nisi ut suam sacramentis virtutem assereret.
Luther cried out with his whole life that he was not contending about anything else except to maintain for the sacraments their proper power. 2
He then proceeds to give his own view (note that what follows is not in indirect statement, which marks a shift to Calvin speaking now for himself). As far as he could tell, at least, Calvin found his own views harmonious with what he took to be the most basic concerns of Luther and Melanchthon:
Convenit, non inanes esse figuras, sed re ipsa praestari quidquid figurant. In baptismo adesse spiritus efficaciam, ut nos abluat et regeneret. Sacram coenam spirituale esse epulum, in quo vere Christi carne et sanguine pascimur.
It is appropriate that [the sacraments] not be empty figures, but that whatever they figure is really given: 3 [namely, that] in baptism the efficacy of the Spirit is present in order to wash and regenerate us; [and that] the sacred supper is a spiritual feast in which we truly feed on the flesh and blood of Christ.
For each sacrament Calvin uses a slightly different construction: for baptism, he employs a clause of purpose, showing the goal or end of baptism (washing and regeneration); for the Supper, a relative clause–and not a relative clause of purpose or characteristic, but one with its verb in the indicative, which highlights the “realism” of the view as it is set forth here, particularly in conjunction with the adverb vere (“truly”).
Timothy Wengert, in “The Epistolary Friendship of John Calvin and Philip Melanchthon,” 4 remarks that “[h]ere is Calvin’s construal of the Wittenberg Concord,” a document signed by Luther, Melanchthon, Bucer, Jonas, Cruciger, and Spalatin (among others) and which I have discussed previously here and here. One can easily see how his position in this letter coheres with the formulations there.
Calvin’s language on the Supper in this passage is not disharmonious with the Variata version of the Augsburg Confession, and is indeed perhaps a touch stronger, somewhere–one might suggest–between the 1530 and 1540 versions of that article, though that is rather a clumsy way of putting it and it must be emphasized that Melanchthon for his entire life saw the 1540 version as nothing more than a gloss on his earlier rendering, completely in accord with it (I may to return to this point in the future, and remember that in this instance Calvin is claiming fundamental agreement with Luther himself). You can compare the two versions of the article here; and see this as well regarding Melanchthon’s view of the Supper.