Higher Homotopy Groups are Abelian

Theorem
Let $T = \left({S, \tau}\right)$ be a topological space.

Let $x_0 \in S$.

Let $n \ge 2$ be a integer.

Let $\pi_n \left({T, x_0}\right)$ be the $n$th homotopy group with base point $x_0$.

Then $\pi_n \left({T, x_0}\right)$ is abelian.