In the long run, mathematics evolves organically and is independent of individual mathematicians. Multiple, and in many cases, almost simultaneous discovery of concepts or proofs of theorems is the norm rather than the exception. Someone will discover the concept or prove the theorem, eventually. Gian-Carlo Rota often praised an idea, detached from its accidental discoverers, as "an idea whose time has come". In the 1960s, the time came for the theory of Möbius functions of partially ordered sets, and the area has flourished since then. Rota did not include his paper Foundations I [4] among his most original papers. In his opinion, he only uncovered a theory already " there".