Karl Marx (German: [ˈkaɐ̯l ˈmaɐ̯ks]; 5 May 1818 – 14 March 1883) was a German philosopher, economist, historian, political theorist, sociologist, journalist and revolutionary socialist.Read about Karl Marx in Wikipedia
Both for the production on a mass scale of this communist consciousness, and for the success of the cause itself, the alteration of men on a mass scale is necessary, an alteration which can only take place in a practical movement, a revolution; this revolution is necessary, therefore, not only because the ruling class cannot be overthrown in any other way, but also because the class overthrowing it can only in a revolution succeed in ridding itself of all the muck of ages and become fitted to found society anew.
[The career a young man should choose should be] one that is most consonant with our dignity, one that is based on ideas of whose truth we are wholly convinced, one that offers us largest scope in working for humanity and approaching that general goal towards which each profession offers only one of the means: the goal of perfection. . . If he works only for himself he can become a famous scholar, a great sage, an excellent imaginative writer [ Dichter ], but never a perfected, a truly great man.