en vehement hyperbole, which is nearly always a
disfigurement in written prose, may become impressive or delightful,
when it harmonises with the voice, the glance, the gesture of a fervid
and exuberant converser. Hence Diderot's personality invested his talk,
as happened in the case of Johnson and of Coleridge, with an imposing
interest and a power of inspiration which we should never comprehend
from the mere perusal of his writings.

His admirers declared his head to be the ideal head of an Aristotle or a
Plato. His brow was wide, lofty, open, gently rounded. The arch of the
eyebrow was full of delicacy; the nose of masculine beauty; the
habitual expression of the eyes kindly and sympathetic, but as he grew
heated in talk, they sparkled like fire; the curves of the mouth bespoke
an interesting mixture of finesse, grace, and geniality. His bearing was
nonchalant enough, but there was naturally in the carriage of his head,
especially when he talked with action, much dignity, energy, and
nobleness. It seemed as if enthusiasm were the natural condition for his
voice, for his spirit, for every feature. He was only truly Diderot when
his thoughts had transported him beyond himself. His ideas were stronger
than himself; they swept him along without the power either to stay or
to guide their movement. "When I recall Diderot," wrote one of his
friends, "the immense variety of his ideas, the amazing multiplicity of
his knowledge, the rapid flight, the warmth, the impetuous tumult of his
imagination, all the charm and all the disorder of his conversation, I
venture to liken his character to nature herself, exactly as he used to
conceive her--rich, fertile, abounding in germs of every sort, gentle
and fierce, simple and majestic, worthy and sublime, but without any
dominating principle, without a master and without a God."[21] Gretry,
the musical composer, declares that Diderot was one of the rare men who
had the art of blowing the spark of genius into flame; the first
impulses stirred by his glowing imagination were of inspiration
divine.[22]

Marmontel warns us that he who only knows Diderot in his writings, does
not know him at all. We should have listened to his persuasive
eloquence, and seen his face aglow with the fire of enthusiasm. It was
when he grew animated in talk, and let all the abundance of his ideas
flow freely from the source, that he became truly ravishing. In his
writings, says Marmontel with obvious truth, he