[2] His father, who was the author of many papers on various subjects, occupied his son of his own studies early, including the works of the Roman poet Lucretius at the age of 13.

Although Le Sage published few papers in his life, he had extensive letter exchanges with people like Jean le Rond d'Alembert, Leonhard Euler, Paolo Frisi, Roger Joseph Boscovich, Johann Heinrich Lambert, Pierre Simon Laplace, Daniel Bernoulli, Firmin Abauzit, Lord Stanhope etc..

He gave private lessons in mathematics, and his pupils, including La Rochefoucauld, Simon Lhuilier, Pierre Prévost, were deeply impressed by his personality.

Le Sage described his manner of thinking and working by saying: I have been born with four dispositions well adapted for making progress in science, but with two great defects in the faculties necessary for that purpose.

Le Sage also clearly pointed out, that he was not the first one who described such a mechanism, and referred to Lucretius, Gassendi, Hermann and Bernoulli.

Never have I had so much satisfaction as at this moment, when I have just explained rigorously, by the simple law of rectilinear motion, those of universal gravitation, which decreases in the same proportion as the squares of the distance increase.

In this paper, entitled "Essai de Chymie Méchanique",[9] he tried to explain both the nature of gravitation and chemical affinities.

Fatio was a well-known Swiss personage, and the kinetic theory of gravitation was his most notable scientific contribution, to which he devoted much of his life.

Nevertheless, Le Sage later claimed that his father never told him that Fatio had created a theory of gravitation essentially identical to his own.

In any case, Le Sage stated that he knew nothing of Fatio's theory until he was informed by his teacher Gabriel Cramer in 1749.

It includes revisions made by Fatio as late as 1743, forty years after he composed the manuscript on which the Bopp edition was based.

Le Sage wrote to Lambert in 1768:[12] "Nicolas Fatio de Duillier had created a theory in 1689, which is so similar to mine, that it only differed in the elasticity, which he has given his intensely agitated matter".

In the "Physique Mécanique" published by Prevost after Le Sage's death, Fatio is mentioned in connection with the net structure of matter, but it goes on to claim that he (Le Sage) had developed the idea of the net structure already in 1763, before he was in possession of Fatio's original papers.

In the same paper, Le Sage repeated the incorrect claim that Fatio assumed "elastic" collisions – and therefore did not really provide a valid explanation of gravity.

In later years Le Sage responded in two different ways to charges that his ideas on gravitation were only the result of studying Cramer's papers.

[13] He went on to ask rhetorically why none of these supposed predecessors (of whom he professes to have no definite knowledge) "pushed these consequences to their conclusion and communicated their research".

He suggested that the answer was that they had no clear view of the subject, had not firmly grasped the principles of the theory, had allowed themselves to be seduced by specious sophisms, had bowed to the authority of great names, or had "lacked sufficient love of truth or courage of their convictions to abandon easy pleasures and exterior advantages in order to devote themselves to researches at the time difficult and little welcome.".

However, although he sometimes referred to those predecessors, he often spoke in a derogatory way about them – see his comments in "Lucrece Newtonien", and his appraisal of Cramer as too vague and scientifically not valuable.