However one might nowadays diagnose the nervous disorder from which Proust suffered, the social mark of his condition was an openness to external stimuli, a kind of porosity that might be called neurasthenic. This attitude of unprotectedness was positive, on the one hand, since it attuned him to the world of sensation, the source of inspiration for the artist. But Proust's awareness of his openness is the source of an acute concern about linguistic dependency and authenticity of language that flavours all his major reflections on literary aesthetics. For this potential writer, the spoken word, which floats in the air between interlocutors, authorless, unassignable, represents language at its most ambivalent and most threatening.

One of Proust's most insightful early readers pictured him as an individual who responded totally to anything that made an impression on him: ‘Proust's soul is a function when seen in relation to the changing variables of reality, of life. It does not represent and does not protect an independent spirituality’, said Ramon Fernandez in the 1940s. French students of characterology have followed in this vein, classifying Proust variously as emotive-non-active-primary, or perhaps secondary, terminology which denotes an emotional, susceptible personality especially permeable to external stimuli.

The Narrator of A la recherche criticizes his open disposition, but recognizes that it facilitates the crucial first step in writing, which is to get into the skin of one's subject: