Moral Letters to Lucilius/Letter 3 - Wikisource, the Free Online Library

Your path to friendship really begins with an absolute trust that God both knows what is best for you and is also working to bring the best into your life. If you do not hold that conviction firmly within your mind, you will forever question every opportunity you are given. You will take your walk down the path of cynicism and away from friendship.

Trust will always be one of the greatest, rarest, and happiest blessings of our life in community, though it can emerge only on the dark background of a necessary mistrust.

As to yourself, although you should live in such a way that you trust your own self with nothing which you could not entrust even to your enemy, yet, since certain matters occur which convention keeps secret, you should share with a friend at least all your worries and reflections.

But if you consider any man a friend whom you do not trust as you trust yourself, you are mightily mistaken and you do not sufficiently understand what true friendship means.

trust everyone or to trust no one; both are faults, but the former is what I might call a more honorable fault, the latter a safer one.