A question about the holonomy group at different basepoints

Question

if $\gamma :I \rightarrow M$ where I is the unit interval, M is a manifold with a connection $\nabla$, $\gamma(0)=x,\gamma(1)=y$ and $P_\gamma$ is the parallel transport map from x to y, why is it that $$Hol_y(\nabla)=P_\gamma Hol_x (\nabla) P_\gamma^{-1}$$ I've tried reasoning this out to try to give myself some intuition for why this is, but to no avail.