  In 1684, Leibniz published a short treatise with the above title. It was his first mature publication and one to which he often referred in the course of his philosophical career. In it, Leibniz sets out a series of distinctions for human knowledge or cognition (cognitio): knowledge is either obscure or clear; clear knowledge is either confused or distinct; distinct knowledge is either inadequate or adequate; and adequate knowledge is either symbolic or intuitive. Now, according to Leibniz, clear knowledge means being able to recognize something that is represented to us, for example, a rose; and knowledge is both clear and distinct when one can enumerate marks sufficient to distinguish a rose from other things. When one can give such an enumeration, one possesses a distinct notion or concept and is thus able to give a nominal definition of the thing. Further, if all the marks that form part of a distinct notion are themselves distinctly known, then the cognition is adequate. And, finally, if a notion is complex and we are able to consider all its component notions simultaneously, then our knowledge of it is intuitive. Ultimately, Leibniz holds that human beings have intuitive knowledge only of primary notions and propositions, whereas God, of course, has intuitive knowledge of all things.