“He who studies without passion will never become anything more than a pedant. We must approach knowledge from the inside; inspired by passion.”

Quoted in the National Hospice and Palliative Care Organization (NHPCO) website https://web.archive.org/web/20120720131254/http://www.caringinfo.org/i4a/pages/index.cfm?pageid=3494 (2012).

Le plaisir de l'amour est d'aimer; et l'on est plus heureux par la passion que l'on a que par celle que l'on donne.
Maxim 259. Compare: "They who inspire it most are fortunate, As I am now; but those who feel it most Are happier still", Percy Bysshe Shelley, Prometheus Unbound, Act ii, Scene 5.
Reflections; or Sentences and Moral Maxims (1665–1678)

1950s, Give Us the Ballot (1957)
Context: This is no day for the rabble-rouser, whether he be Negro or white. We must realize that we are grappling with the most weighty social problem of this nation, and in grappling with such a complex problem there is no place for misguided emotionalism. We must work passionately and unrelentingly for the goal of freedom, but we must be sure that our hands are clean in the struggle. We must never struggle with falsehood, hate, or malice. We must never become bitter. I know how we feel sometime. There is the danger that those of us who have been forced so long to stand amid the tragic midnight of oppression—those of us who have been trampled over, those of us who have been kicked about—there is the danger that we will become bitter. But if we will become bitter and indulge in hate campaigns, the new order which is emerging will be nothing but a duplication of the old order.

Biographia Literaria, introduction (1906).

Global Ideas from Pluto's Challenger (May 21, 2009)
Context: The best educators are the ones that inspire their students. That inspiration comes from a passion that teachers have for the subject they're teaching. Most commonly, that person spent their lives studying that subject, and they bring an infectious enthusiasm to the audience.I think many people have that enthusiasm, but they are prevented from being teachers because they didn't go through the teacher mill. Now you have teachers who have been through the teacher mill, yet they have no capacity to inspire anyone at all. It's the inspired student that continues to learn on their own. That's what separates the real achievers in the world from those who pedal along, finishing assignments.

Source: Treatise Concerning Eternal and Immutable Morality (1731), Ch. 1, sct. 1

Les passions sont les seuls orateurs qui persuadent toujours. Elles sont comme un art de la nature dont les règles sont infaillibles; et l'homme le plus simple qui a de la passion persuade mieux que le plus éloquent qui n'en a point.
Variant translation: The passions are the only orators who always persuade. They are like a natural art, of which the rules are unfailing; and the simplest man who has passion will be more persuasive than the most eloquent man who has none.
Maxim 8.
Reflections; or Sentences and Moral Maxims (1665–1678)

Source: Sad Cypress