Law of Simple Conversion of I

Theorem
Consider the particular affirmative categorical statement Some $S$ is $P$:
 * $\mathbf I \left({S, P}\right): \exists x: S \left({x}\right) \land P \left({x}\right)$

Then Some $P$ is $S$:
 * $\mathbf I \left({P, S}\right)$