Criticism, for Baudelaire, whether of art, music or literature, was at its best when it was amusing, poetic and impassioned, and when it was driven by an urgent intellectual desire to deduce the reasons that justify the emotion these arts aroused (OC II 127). That emotion was at times so intense as to provoke a physical reaction: thus, recalling the first time he read the works of the poet, novelist and critic Théophile Gautier, Baudelaire asserts that his admiration for Gautier's skill was strong enough to create in him a kind of nervous convulsion (OC II 118). Finding a way of understanding that reaction, and conveying it in writing, dominates much of his criticism, giving it its particular savour and edge.

Indeed, to understand those reactions and to represent a work well, Baudelaire asserts in an article published in 1851, you need to get inside its skin. This expression, which he puts in italics to signify its novelty, had recently been created by an actor explaining his technique for conveying characters (OC II 1094). It is typical of Baudelaire's interest in the modern and his ability to transfer concepts created for one genre to another different genre that he seizes with such energy and acumen on this term from the theatre. In his literary criticism, Baudelaire constantly attempts to get inside the skin of the work he is reviewing, devoting considerable intellectual energy to analysing the writings of his contemporaries, not merely the well known, like Victor Hugo, Gustave Flaubert and Théophile Gautier, but also lesser-known figures such as the worker poet, Pierre Dupont, and Marceline Desbordes-Valmore, whose Elégies (1819) was the first volume of Romantic poetry published in France.