We must believe that "emotion recollected in tranquillity" is an inexact formula. For it is neither emotion, nor recollection, nor without distortion of meaning, tranquillity. It is a concentration, and a new thing resulting from the concentration of a very great number of experiences which to the practical and active person would not seem to be experiences at all; it is a concentration which does not happen consciously or of deliberation. These experiences are not "recollected" and they finally unite in an atmosphere which is "tranquil" only in that it is a passive attending upon the event.
"Reading Prose: An Introduction to Critical Study". Book by T. S. Eliot (p. 505), 1952.