But oh! the blessing it is to have a friend to whom one can speak fearlessly on any subject

Thus ended our little talk: yet it left a pleasant impression. True, the subject was strange enough; my sisters might have been shocked at it; and at my freedom in asking and giving opinions. But oh! the blessing it is to have a friend to whom one can speak fearlessly on any subject; with whom one's deepest as well as one's most foolish thoughts come out simply and safely. Oh, the comfort—the inexpressible comfort of feeling safe with a person—having neither to weigh thoughts nor measure words, but pouring them all right out, just as they are, chaff and grain together; certain that a faithful hand will take and sift them, keep what is worth keeping, and then with the breath of kindness blow the rest away.

Somebody must have done a good deal of the winnowing business this afternoon; for in the course of it I gave him as much nonsense as any reasonable man could stand ...

Dinah Maria (Mulock) Craik, A Life for a Life

Often misattributed to George Eliot. You may find out more about that and the book which this quote is from here.