(Continuing a recent line of inquiry.)
It is well known that Calvin assented to or subscribed the Augsburg Confession, whether as a formal act or in some other way. Lest there be any doubt, Calvin himself says so in a letter of March 1557 to Schallingius. There is much in the letter of interest, and so I may return to it later. For the moment, however, just the passage on the Confession, which reads as follows:
Nec vero Augustanam confessionem repudio, cui pridem volens ac libens subscripsi, sicuti eam autor ipse interpretatus est.
“Nor indeed do I reject the Augsburg Confession, which long ago I willingly and gladly subscribed, as the author himself interpreted it.”
Calvin would have subscribed the Confession in 1540-41, which means that even 16/17 years later Calvin can still express his hearty agreement with it; note that he signed it volens ac libens. He further specifies the spirit in which he signed it: sicuti eam autor ipse interpretatus est. The autor ipse is of course Melanchthon, and intpretatus est probably indicates that he means the Augsburg Variata rather than the Invariata, as Timothy Wengert remarks.
All in all, an illuminating little window into 16th century Protestant confessionalism, so very different from that of our own age.