Theodore Beza’s “Life of Calvin” in John Calvin, John Calvin: Tracts and Letters, 1.xcvii-xcix. As always, emphasis is mine.
He [Calvin] lived 54 years, 10 months, 17 days, the half of which he spent in the ministry. He was of moderate stature, of a pale and dark complexion, with eyes that sparkled to the moment of his death, and bespoke his great intellect. In dress he was neither over careful nor mean, but such as became his singular modesty. In diet he was temperate, being equally averse to sordidness and luxury. He was more sparing in the quantities of his food, and for many years took only one mean a-day, on account of the weakness of his stomach. He took little sleep, and had such an astonishing memory, that any person whom he had once seen he instantly recognized at the distance of years, and when, in the course of dictating, he happened to be interrupted for several hours, as often happened, as soon as he returned he commenced at once to dictate where he had left off. Whatever he required to know for the performance of his duty, though involved in a multiplicity of other affairs, he never forgot. On whatever subject he was consulted, his judgment was so clear and correct, that he often seemed almost to prophesy; nor do I recollect of any person having been led into error in consequence of following his advice. He despised mere eloquence, and was sparing in the use of words, be he was by no means a careless writer. No theologian of this period (I do not speak invidiously) wrote more purely, weightily, and judiciously, though he wrote more than any individual either in our recollection or that of our fathers. For, by the hard studies of his youth, and a certain acuteness of judgment, confirmed by practice in dictating, he was never at a loss for an appropriate and weighty expression, and wrote very much as he spoke. In the doctrine which he delivered at the first, he persisted steadily to the last, scarcely making any change. Of few theologians within our recollection can the same thing be affirmed. With regard to his manners, although nature had formed him for gravity, yet, in the common intercourse of life, there was no many who was more pleasant. In bearing with infirmities he was remarkably prudent; never either putting weak brethren to the blush, or terrifying them by unreasonable rebuke, yet never conniving at or flattering their faults. Of adulation, dissimulation, and dishonestly, especially where religion was concerned, he was as determined and severe an enemy as he was a lover of truth, simplicity, and candour. He was naturally of a keen temper, and this had been increased by the very laborious life which he had led. But the Spirit of the Lord had so taught him to command his anger, that no word was heard to proceed from him unbecoming a good man. Still less did he ever allow his passions to proceed to extremes. Nor was he easily moved, unless when religion was at stake, though he had to do with men of a petulant and obstinate temper.