Full Idea
Morality acts to prevent the rise of new and better mores: it stupefies.
Clarification
'mores' are customs
Gist of Idea
Morality prevents us from developing better customs
Source
Friedrich Nietzsche (Dawn (Daybreak) [1881], 019)
Book Reference
Nietzsche,Friedrich: 'Dawn (Daybreak) (v 5)', ed/tr. Smith, Brittain [Stanford 2011], p.20
A Reaction
Note that he wants 'better' customs, and not just different ones. So the deep question concerns the criteria for why some customs are better. He seems to want us to fulfil our natures more completely. Arts, sciences, great deeds...