Given a S$\mathbb{S}$-module, we can construct a Schur functor, which is an endo functor in the category of vectorspaces. But given a Schur functor, how can we get back the S$\mathbb{S}$-module? In Loday Vallette's book on OperadsLoday/Vallette's book on Operads, they say that if P$P$ is the Schur functor, look at P(V)$P(V)$, where V$V$ is an n$n$-dimensional vectorspace. The n multilinear$n$-multilinear part of P(V)$P(V)$ is isomorphic to P(n)$P(n)$, as a S_n modulean $S_n$-module. Can someone explain what is meant by the 'multilinear part'?