The Metaphysics of Morals by Immanuel Kant Chapter 2 Page 46

(in order to arrange my examples). For the rest, I understand by a perfect duty one that admits no exception in favour of inclination and then I have not merely external but also internal perfect duties. This is contrary to the use of the word adopted in the schools; but I do not intend to justify there, as it is all one for my purpose whether it is admitted or not.

1. A man reduced to despair by a series of misfortunes feels wearied of life, but is still so far in possession of his reason that he can ask himself whether it would not be contrary to his duty to himself to take his own life.

Now he inquires whether the maxim of his action could become a universal law of nature. His maxim is: “From self-love I adopt it as a principle to shorten my life when its longer duration