T. S. Eliot, "Tradition and the Individual Talent" (1920)

One error, in fact, of eccentricity in poetry is to seek for new human emotions to express; and in this search for novelty in the wrong place it discovers the perverse. The business of the poet is not to find new emotions, but to use the ordinary ones and, in working them up into poetry, to express feelings which are not in actual emotions at all. And emotions which he has never experienced will serve his turn as well as those familiar to him. Consequently, 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. Of course this is not quite the whole story. There is a great deal, in the writing of poetry, which must be conscious and deliberate. In fact, the bad poet is usually unconscious where he ought to be conscious, and conscious where he ought to be unconscious. Both errors tend to make him “personal.” Poetry is not a turning loose of emotion, but an escape from emotion; it is not the expression of personality, but an escape from personality. But, of course, only those who have personality and emotions know what it means to want to escape from these things.

Cf. Fernando Pessoa, "Autopsicografia" (1932)

O poeta é um fingidor. 
Finge tão completamente 
Que chega a fingir que é dor 
A dor que deveras sente. 

E os que lêem o que escreve, 
Na dor lida sentem bem, 
Não as duas que ele teve, 
Mas só a que eles não têm.

E assim nas calhas de roda 
Gira, a entreter a razão, 
Esse comboio de corda 
Que se chama o coração.