Religion is nothing if it be not the vital act by which the entire mind seeks to save itself by clinging to the principle from which it draws its life.
 William James, The Varieties of Religious Experience (1902). copy citation

Context

“Prayer is religion in act; that is, prayer is real religion. It is prayer that distinguishes the religious phenomenon from such similar or neighboring phenomena as purely moral or æsthetic sentiment. Religion is nothing if it be not the vital act by which the entire mind seeks to save itself by clinging to the principle from which it draws its life. This act is prayer, by which term I understand no vain exercise of words, no mere repetition of certain sacred formulæ, but the very movement itself of the soul, putting itself in a personal relation of contact with the mysterious power of which it feels the presence,—it may be even before it has a name by which to call it.” source