Lagrange’s Memoirs. 109 
His features were moulded after death, and previously while he 
slunabered, a — was made of him that was said to be very 
correct. 
Sweet, and even sini in conversation, he loved particularly to 
interrogate, either to show the worth of others, or to add their re- 
flections to his vast knowledge. When he spoke, it was always in 
the strain of a doubt, and his first phrase generally began with je ne 
sais pas. He respected all opinions, and was very far. from giving © 
his own as rules. Nor was it easy for him to change them. For 
he sometimes defended them with a warmth that went on increasing 
until he perceived some change in himself; then he returned to his 
usual tranquillity. One day, after a dispute of this sort, Lagrange 
having gone out, Borda, remaining alone with me, let slip these 
words ; Je suis faché d’ avoir a le dire d’ un homme tel que M. La- 
grange, mais je n’ en connais pas de plus entété. If Borda had gone 
out first, Lagrange doubtless would have said the same of his brother, 
aman of sense and much talent. He too, like Lagrange, would 
not readily change ideas adopted only after a thorough examination. 
ften was remarked in his tone a light and sweet irony, the 
meaning of which it was possible to mistake, and at which I have 
seen no instance where any one could have felt offended. Thus he 
said to me one day: ‘These astronomers are singular; they will 
not believe a theory, where it does not agree with their observations.” 
The looks of him who made this reflection, on uttering it; marke 
sufficiently its real meaning. I did not think myself obliged to de- 
fend astronomers. 
-Among so many fnaivorspioed that are due to his genius, his 
Mecanique is unquestionably the most grand, remarkable and impor- 
tant. The fonctions analytique are only secondary, notwithstanding 
the fruitfulness of the principal idea, and the beauty of the devel- 
opments. A notation less convenient, calculations more embarrass- 
ing, although more luminous, will prevent geometers from employing, 
unless in certain difficult and doubtful cases, his symbols and. his 
demonstrations ; it suffices that he has supported them on the law- 
fulness of the more expedient methods of the differential and inte- 
gral calculus. He himself has followed the usual notation in the 
second edition of his Mecanique. 
This great work is wholly founded on the calculus of which he 
is the inventor. Every thing in it flows from a single formula, and 
from a principle known before him, but of which the whole use was 
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