Spinoza to Blyenbergh Unknown Friend, I received, at Schiedam, on the 26th of December, your letter dated the 12th of December, enclosed in another written on the 24th of the same month. I gather from it your fervent love of truth, and your making it the aim of all your studies. This compelled me, though by no means otherwise unwilling, not only to grant your petition by answering all the questions you have sent, or may in future send, to the best of my ability, but also to impart to you everything in my power, which can conduce to further knowledge and sincere friendship. It is, moreover, the highest and most pleasing source of happiness derivable from things not under our own control.
Nothing save truth has power closely to unite different feelings and dispositions.
I say nothing of the very great advantages which it brings, lest I should detain you too long on a subject which, doubtless, you know already. I have said thus much, in order to show you better how gladly I shall embrace this and any future opportunity of serving you. In order to make the best of the present opportunity, I will at once proceed to answer your question. This seems to turn on the point that it seems to be clear, not only from God's providence, which is identical with His will, but also from God's co-operation and continuous creation of things, either that there are no such things as sin or evil, or that God directly brings sin and evil to pass. You do not, however, explain what you mean by evil.