It would not be an overstatement to assert that the release of Newton’s Principia was akin to a tidal wave inundating the European scientific community in the final years of the seventeenth century. Newton’s theories would overshadow discussions in both mechanics and astronomy until at least the mid-point of the subsequent century.
In his account of Newton’s life, Richard Westfall wrote:
Nonetheless, the realm of natural philosophy was unprepared for the Principia. The increasing astonishment of Edmond Halley as he reviewed successive drafts of the work was echoed countless times in individual instances. Almost immediately after its release, even those who did not accept its core notion of action at a distance acknowledged the Principia as a landmark publication. A pivotal moment for Newton, who, after two decades of abandoned inquiries, had at last completed a significant endeavor, the Principia also marked a crucial juncture for natural philosophy.[1]
The arrival of the book was not entirely unforeseen. Speculation had been rife for much of 1687, and just before its release, a comprehensive review was published in the Philosophical Transactions of the Royal Society, which was, after all, the official publisher. The review bore no signature; however, it is known that Halley authored it. This raises various ethical concerns. The review, which outlines the Principia, commences:
The unparalleled Author, having eventually been convinced to make a public appearance, has in this Treatise provided a remarkable example of the extent of the powers of the Mind; and has simultaneously demonstrated what the Principles of Natural Philosophy are, and derived from them their implications to such an extent that he seems to have exhausted his Argument, leaving little for those who will follow him.[2]
The entire British mathematical circle was anxious to obtain a copy of this remarkable work and, upon doing so, quickly realized that it contained a substantial amount of material to digest. John Locke (1632–1704), at the time a political exile residing on the European mainland, quickly recognized that the mathematics was beyond his grasp, prompting him to inquire with Christiaan Huygens (1629–1695) about the soundness of the mathematics. When Huygens affirmed its validity, Locke endeavored to understand the propositions without the mathematical demonstrations.
Robert Hooke (1635–1703), who had vocally claimed during the writing of the book that he should be credited as the originator of the law of gravity, nearly drove Newton to forsake Book III. Upon seeing what he believed had been taken from him, he protested even more loudly but was simply disregarded.
Newton’s book received just as enthusiastic a reception on the Continent as in Britain, with comprehensive reviews appearing in the spring and summer of 1688 in three of the leading journals: the Bibliothèque universelle in the Netherlands, the Journal des sçavans in France, and the Acta eruditorum in Germany.
The review in Bibliothèque universelle was solely a descriptive outline and was most likely written by John Locke. The Journal des sçavans asserted that it showcased “the most perfect mechanics imaginable,” yet vehemently dismissed Newton’s physical concept—action at a distance. The Acta eruditorum allocated a total of eighteen pages to their review, which warmly lauded the book.
Halley sent copies of the Principia to prominent natural philosophers in the Continent, including Christiaan Huygens (1629–1695) and Gottfried Leibniz (1646–1716), both of whom were greatly impressed by Newton’s work, though both rejected the notion of action at a distance, with Huygens describing it as absurd. Nevertheless, he informed his brother that he admired “the beautiful discoveries found in the work he sent me.”[3]
Huygens paid his respects to Newton during his visit to London in 1689. From that point until his death in 1695, his correspondence with Newton was heavily focused on themes related to the theories elaborated in the Principia. The same holds true for the exchange of letters between Newton and Leibniz. Their intense interest in all aspects of the Principia, which dominated their correspondence, evidenced that with its release, Newton had ascended to the highest echelons of European natural philosophers.
In his letters, Leibniz asserted that gravity must have a physical cause in the form of an aethereal vortex, akin to Descartes, a concept that Newton firmly rejected.
Nevertheless, Newton himself was quite uncomfortable with the notion of action at a distance, as he expressed in a letter to Richard Bentley (1662–1742) in 1692:
That one body may act upon another at a distance through a vacuum without the mediation of anything else…is to me so great an absurdity that I believe no man who possesses a competent capacity for philosophical thought can ever accept it.
Newton explored various concepts to explain gravity, including a type of aethereal rationale suggested by the Swiss mathematician.