How skillful he is both in public and in private law! What a knowledge he possesses of things, of examples, and of antiquity! There is nothing you would learn which he cannot teach. In every difficulty he is my constant resource.
Quam peritus ille et privati iuris et publici! quantum rerum, quantum exemplorum, quantum antiquitatis tenet! Nihil est quod discere velis quod ille docere non possit; mihi certe quotiens aliquid abditum quaero, ille thesaurus est.
Original text (Latin)
Source, in full
Letter 22, 2. On Titius Aristo. Reported in J. W. Jones, A Translation of all the Greek, Latin, Italian, and French Quotations which Occur in Blackstone's 'Commentaries on the Laws of England', &c. (Philadelphia, PA: T. & J. W. Johnson & Co, 1889) p. 1