Timothy Zahn said this quote

A friend need not be kept either within sight or within reach. A friend must be allowed the freedom to find and follow his own path. If one is fortunate, those paths will for a time join. But if the paths separate, it is comforting to know that a friend still graces the universe with his skills, and his viewpoint, and his presence. For if one is remembered by a friend, one is never truly gone.