The name given by Ruskin to a series of letters to workmen, written during the seventies of this century, and employed by him to designate three great powers which go to fashion human destiny, viz., Force, wearing, as it were, (clava) the club of Hercules; Fortitude, wearing, as it were, (clavis) the key of Ulysses; and Fortune, wearing, as it were, (clavus) the nail of Lycurgus; that is to say, Faculty waiting on the right moment, and then striking in. See Shakespeare's "Time and tide in the affairs of men," etc., the "flood" in which is the "Third Fors." The letters are represented as written at the dictation of the Third Fors, or, as it seems to the author, the right moment, or the occurrence of it.