Schopenhauer's Shares in Spinoza

Schopenhauer dealt intensively with Spinoza throughout his whole life. This includes not only enthusiastic agreement, but also harsh rejection. Spinoza's peculiar use of words caused some misunderstandings, which are clarified here. In the course of this, it turns out that Schopenhauer's fundamental view is the same as Spinoza's, which he does not even acknowledge.
According to Schopenhauer, Spinoza fails to solve the problem of all ethics, and he provides a fix by borrowing some of Spinoza's own ideas and giving his metaphysics a twist.