The Categorical imperative (n.) is about applying the perfect law in the imperfect state in order to to create the ideal community by acting as if we already belonged to it.
The Categorical imperative (n.) is grounded in that idea that you must treat humanity, whether in thine own person or in that of another, in every case as an end, never only as a means.
The Categorical imperative (n.) is not about happiness, but about perfection, regardless of it it brings us happiness or pain.
The Categorical imperative (n.) is not properly the doctrine how we may make ourselves happy, but how we may make ourselves worthy of happiness.
The Categorical imperative (n.) is that an action is good not because it has good results, or because it is wise, but because it is done in obedience to this inner sense of duty.
The Categorical imperative (n.) is nothing but this: Act only on that maxim whereby thou canst at the same time will that it should become a universal law.