The moral law invigorates and ennobles the agent because it originates from the agent's own reason and represents her higher self and vocation, producing pleasure
Even though we cannot know (or “make intelligible a priori”) how a thought or judgment about the morality of an action “can itself produce a sensation of pleasure or pain”, Kant thinks that this somehow does happen; it must, if moral considerations are to be motivating in beings like us. The phenomenology of respect is unusual, as it involves both pain and pleasure (or something like it). There is the humiliation an agent feels when the moral law strikes down her self-conceit; but respect also f