How selfish soever man may be supposed, there are evidently some principles in his nature, which interest him in the fortune of others, and render their happiness necessary to him, though he derives nothing from it, except the pleasure of seeing it.
Human beings are not intrinsically selfish, which isolates us from others. We are essentially social animals who depend on others to meet our needs. We achieve happiness, prosperity and progress through social interaction. Therefore, having a kind and helpful attitude contributes to our own and others' happiness.
Some say that happiness is not good for mortals, & they ought to be answered that sorrow is not fit for immortals & is utterly useless to any one; a blight never does good to a tree, & if a blight kill not a tree but it still bear fruit, let none say that the fruit was in consequence of the blight.
The true measure of a career is to be able to be content, even proud, that you succeeded through your own endeavors without leaving a trail of casualties in your wake.