MDDM CH 75.743 (Hume)

[Terrance]

He turns to the Straps securing the Transit Instruments, ignoring what
is just behind his Eyes and Nose. "Mind thyself, Friend." 

It is needless to push our researches so far as to ask, why we have
humanity or a fellow-feeling with others. It is sufficient, that this is
experienced to be a principle in human nature. We must stop somewhere in
our examination of causes; and there are, in every science, some general
principles, beyond which we cannot hope to find any principle more
general. No man is absolutely indifferent to the happiness and misery of
others. The first has a natural tendency to give pleasure; the second,
pain. This
every one may find in himself. It is not probable, that these principles
can be resolved into principles more simple and universal....


HUME, AN ENQUIRY CONCERNING THE PRINCIPLES OF MORALS