For Roland Barthes, Photography is the absolute Partial, the supreme Chance, the Opportunity, the Encounter, the Real, in its thorough expression. An "ontological" desire had seized him regarding Photography.

Through these texts, he attempts to learn what it is "in itself," what essential characteristic distinguishes it from the community of images. The research he began led him to wonder: "Why shouldn’t there, in some way, be a new science as an object? A Mathesis singularis (and no longer Mathesis universalis)?"

Thus, I accepted to consider myself a mediator of all Photography: I would try to formulate, based on some personal initiatives, the fundamental characteristic, the universal without which there is no Photography.

[Excerpt from the text on the back cover of the edition]