Date: 1761

"It is not the soft power of humanity, it is not that feeble spark of benevolence which Nature has lighted up in the human heart, that is thus capable of counteracting the strongest impluses of self-love."

— Smith, Adam (1723-1790)

Date: 1765

"Modern philosophers give them other fine names and Julius Scaliger, in particular, used to call them "seeds of eternity" and also "zopyra"--meaning living fires or flashes of light hidden inside us but made visible by stimulation of the senses, as sparks can be struck by steel."

— Leibniz, Gottfried Wilhelm (1646-1716)

Date: 1782

"I read it carefully a second time--pondered--weighed--and submitted--whenever a spark of vanity seems to be glowing at my heart--I will read your letter--and what then?"

— Sancho, Charles Ignatius (1729-1780)