One day, finding his discourses useless, Calvin determined to present him with 'a treatise of his;'[792] that is all he says. He does not mention the title of this work; but as it cannot have been either his commentary on Seneca's _De Clementiâ_ or the _Psychopannichia_, it was evidently the _Institutes of the Christian Religion_, which he had just printed at Basle—these three works being at that time all the reformer had written. Even on the supposition that Calvin had left Basle before the actual publication of his book, it would have been very natural for him to take a copy with him when starting for Italy. Master François opened that volume, which, by God's grace, has imprinted indelible convictions in so many minds. This is the first notice we have of the reading of the _Institutes_: it is mentioned by Calvin himself, and took place during his Italian journey, in the castle of Lucrezia Borgia's son. These circumstances impart to it a peculiar interest. François probably did not read the whole treatise. The mass was the subject of difference between him and Calvin, and consequently it was that part of his work to which the latter referred him. There was much in it calculated to disturb the chaplain. 'Christ,' said the treatise, 'being immortal, has been appointed by God everlasting priest; he has no need then for others to succeed him. Now do not those priests who offer sacrifice every day put themselves in Christ's place, and rob him of the prerogative of his eternal sacrifice?'[793] Further on he adds: 'The mass being established in such a manner that a hundred thousand sacrifices are offered up daily, swamps and buries the sacrifice of Christ which was offered as _sole_ sacrifice. To set up an altar now is to pull down the cross of Jesus Christ. The mass blots out of the remembrance of men the Saviour's true and only death.' And still further on the chaplain read: 'The mass robs us of the fruits which resulted to us from the death of Christ; for who will believe himself redeemed by that death, when a new redemption is presented to him in the mass?' Other considerations put forward by Calvin in his book, were equally calculated to convince the priest.