Timothy Zahn said this quote

“ It is said that one should keep one's allies within view, and one's enemies within reach.A valid statement. One must be able to read an ally's strengths, so as to determine how to best use them. One must similarly be able to read his enemy's weaknesses, so as to determine how to best defeat him.But what of friends?There is no accepted answer, perhaps true friendship is so exceedingly rare. But I had formulated my own.A friend need not be kept 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 paths separate, it is comforting to know that a friend still graces the universe with his skills, and his viewpoint, and his present. For if one is remembered by a friend, one is never truly gone. ”