Definition of "friendship"

But (as the Poet ſaith) Malè ſarta gratia, nequicquam coit, & reſcinditur: Friendſhip, that is but euill peeced, will not ioine cloſe, but falleth aſunder againe:

1570, William Lambard, quoting Horace, A Perambulation of Kent‎, published 1596, page 341

We cannot tell the precise moment when friendship is formed. As in filling a vessel drop by drop, there is at last a drop which makes it run over; so in a series of kindnesses there is at last one which makes the heart run over.

1816 , James Boswell, quoting Samuel Johnson, The life of Samuel Johnson […] ‎, volume 3, T. Cadell and W. Davies, page 181

Friendship is unnecessary, like philosophy, like art, like the universe itself (for God did not need to create). It has no survival value; rather it is one of those things which give value to survival.

1960, C. S. Lewis, The Four Loves, HarperCollins, published 2010