Categorization is produced by a co-individuation process. For example, when Albert Enstein defined, and therefore categorized, general relativity, it was a result of processes of co-individuation of Albert Einstein with numerous people, including with himself. This co-individuation process leads to — and Plato said the same thing in different words — a transindividuation process, that is to say that at a certain point, a metastabilization of rules takes place, and these rules can be specified, shared and taught. However, transindivisduation requires tertiary retentions: Albert Einstein must concretise his calculations and proofs on the pages of books in order to transmit them, open them up to re-readings and criticisms, and give rise to a polemic that constitutes knowledge.