“Being good is the same as being a philosopher. If you obey your father, you will follow the will of a man; if you choose the philosopher's life, the will of God. It is plain, therefore, that your duty lies in the pursuit of philosophy.”

Section 1 : Of The Different Species of Philosophy
Source: An Enquiry Concerning Human Understanding (1748)
Context: Nature has pointed out a mixed kind of life as most suitable to the human race, and secretly admonished them to allow none of these biases to draw too much, so as to incapacitate them for other occupations and entertainments. Indulge your passion for science, says she, but let your science be human, and such as may have a direct reference to action and society. Abstruse thought and profound researches I prohibit, and will severely punish, by the pensive melancholy which they introduce, by the endless uncertainty in which they involve you, and by the cold reception which your pretended discoveries shall meet with, when communicated. Be a philosopher; but, amidst all your philosophy, be still a man.

Conversations with Žižek by Slavoj Žižek and Glyn Daly (Cambridge: Polity Press, 2004), p. 54

Book I, ch. 13.
Discourses

Source: Biographia Literaria (1817), Ch. XV

Source: The Well of Ascension

Incommensurables donc, mais aussi inséparables. Pas de discours qui mérite d’être appelé philosophique, s’il est séparé de la vie philosophique, pas de vie philosophique, si elle n’est étroitement liée au discours philosophique. C’est là d’ailleurs que réside le danger inhérent à la vie philosophique: l’ambiguïté du discours philosophique.
Qu'est-ce que la philosophie antique? (1995)

Source: Dictionary of Burning Words of Brilliant Writers (1895), P. 435.

1950s, The Russell-Einstein Manifesto (1955)