From Petrarch’s proem to his Secret Book:
Tuque ideo, libelle, conventus hominum fugiens, mecum mansisse contentus eris, nominis proprii non immemor. Secretum enim meum es et diceris; michique in altioribus occupato, ut unumquodque in abdito dictum meministi, in abdito memorabis. (via petersadlon.com)
And J.G. Nichols’ translation thereof:
Therefore, little book, avoid the places where men assemble, and be content to stay with me, remembering the name which I have given you. You are my secret book, and so you shall be called. When I think about important matters, what you have recorded in secret will be recalled in secret.