If I were to speak your kind of language, I would say that man's only moral commandment is: Thou shalt think.
But a 'moral commandment' is a contradiction in terms. The moral is the chosen, not the forced; the understood, not the obeyed.
The moral is the rational, and reason accepts no commandments.
If I were to speak your kind ...
Quotes from the same author
If you want to know the one reason that's taking me back, I'll tell you: I cannot bring myself to abandon to destruction all the greatness of the world, all that which was mine and yours, which was made by us and is still ours by right - because I cannot believe that men refuse to see, that they can remain blind and deaf to us forever, when the truth is ours and their lives depend on accepting it.