In “The Virtue of Selfishness”, Ayn Rand wrote:

Ethics is not a mystic fantasy—nor a social convention—nor a dispensable, subjective luxury. … Ethics is an objective necessity of man’s survival—not by the grace of the supernatural nor of your neighbors nor of your whims, but by the grace of reality and the nature of life.

I wish I could write like her although her sentences often feel one size too big for me.