offended at Mr. Whiston for having represented him as an Arian; and so much did he resent the conduct of his friend in ascribing to him heretical opinions, that he would not permit him to be elected a Fellow of the Royal Society while he was President.*

The only other religious works which were composed by Sir Isaac Newton were his Lexicon Propheticum, to which was added a Dissertation on the sacred cubit of the Jews, and Four Letters addressed to Dr. Bentley, containing some arguments in proof of a Deity.

The Lexicon Propheticum was left incomplete, and has not been published; but the Latin Dissertation which was appended to it, in which he shows that the cubit was about 263 Roman unciæ, was published in 1737 among the Miscellaneous Works of Mr. John Greaves.

Upon the death of the Honourable Robert Boyle, on the 30th of December, 1691, it was found, by a codicil to his will, that he had left a revenue of 50%. per annum to establish a lectureship, in which eight discourses were to be preached annually in one of the churches of the metropolis, in illustration of the evidences of Christianity, and in opposition to the principles of infidelity. Dr. Bentley, though a very young man, was appointed to preach the first course of sermons, and the manner in which he discharged this important duty gave the highest satisfaction, not only to the trustees of the lectureship, but to the public in general. In the first six lectures Bentley exposed the folly of atheism even in reference to the present life, and derived powerful arguments for the existence of a Deity from the faculties of the soul, and the structure and functions of the human frame. In order to complete his plan, he proposed to devote his seventh and eighth lectures to the demonstration of a Divine Providence from the physical constitu

* Whiston's Memoirs of his own Life, p. 178, 249, 250. Edit. 1753.

tion of the universe, as established in the Principia. In order to qualify himself for this task, he received from Sir Isaac written directions respecting a list of books necessary to be perused previous to the study of that work;* and having made himself master of the system which it contained, he applied it with irresistible force of argument to establish the existence of an overruling mind. Previous to the publication of these lectures, Bentley encountered a difficulty which he was not able to solve, and he prudently transmitted to Sir Isaac during 1692 a series of queries on the subject. This difficulty occurred in an argument urged by Lucretius, to prove the eternity of the world from an hypothesis of deriving the frame of it by mechanical principles from matter endowed with an innate power of gravity, and evenly scattered throughout the heavens. Sir Isaac willingly entered upon the consideration of the subject, and transmitted his sentiments to Dr. Bentley in the four letters which have been noticed in a preceding chapter.

In the first of these letters Sir Isaac mentions that when he wrote his treatise about our system, viz. the Third Book of the Principia," he had an eye upon such principles as might work, with considering men, for the belief of a Deity, and he expresses his happiness that it has been found useful for that purpose. In answering the first query of Dr. Bentley, the exact import of which we do not know, he states, that, if matter were evenly diffused through a finite space, and endowed with innate gravity, it would fall down into the middle of the space, and form one great spherical mass; but if it were diffused through an infinite space, some of it would collect into one mass, and some into another,

* Dr. Monk's Life of Bentley, p. 31.

Dated December 10th, 1692. This letter is endorsed, in Bentley's hand, "Mr. Newton's answer to some queries sent by me after I had preached my two last sermons,' s."-Monk's Life of Bentley, p. 34, note,

so as to form an infinite number of great masses. In this manner the sun and stars might be formed if the matter were of a lucid nature. But he thinks it inexplicable by natural causes, and to be ascribed to the counsel and contrivance of a voluntary Agent, that the matter should divide itself into two sorts, part of it composing a shining body like the sun, and part an opaque body like the planets. Had a natural and blind cause, without contrivance and design, placed the earth in the centre of the moon's orbit, and Jupiter in the centre of his system of satellites, and the sun in the centre of the planetary system, the sun would have been a body like Jupiter and the earth, that is, without light and heat, and consequently he knows no reason why there is only one body qualified to give light and heat to all the rest, but because the Author of the system thought it convenient, and because one was sufficient to warm and enlighten all the rest.

To the second query of Dr. Bentley, he replies that the motions which the planets now have could not spring from any natural cause alone, but were impressed by an intelligent Agent. "To make such a system with all its motions required a cause which understood and compared together the quantities of matter in the several bodies of the sun and planets, and the gravitating powers resulting from thence; the several distances of the primary planets from the sun, and of the secondary ones from Saturn, Jupiter, and the earth, and the velocities with which those planets could revolve about those quantities of matter in the central bodies; and to compare and adjust all these things together in so great a variety of bodies, argues that cause to be not blind and fortuitous, but very well skilled in mechanics and geometry."

In the second* letter, he admits that the spherical

* Dated Jan. 17th, 1692-3.

mass formed by the aggregation of particles would affect the figure of the space in which the matter was diffused, provided the matter descends directly downwards to that body, and the body has no diurnal rotation; but he states, that by earthquakes loosen. ing the parts of this solid, the protuberance might sink a little by their weight, and the mass by degrees approach a spherical figure. He then proceeds to correct an error of Dr. Bentley's in supposing that all infinites are equal. He admits that gravity might put the planets in motion, but he maintains that, without the Divine power, it could never give them such a circulating motion as they have about the sun, because a proper quantity of a transverse motion is necessary for this purpose; and he concludes that he is compelled to ascribe the frame of this system to an intelligent Agent.

The third letter contains opinions confirming or correcting several positions which Dr. Bentley had laid down, and he concludes it with a curious examination of the opinion of Plato, that the motion of the planets is such as if they had been all created by God in some region very remote from our system, and let fall from thence towards the sun, their falling motion being turned aside into a transverse one whenever they arrived at their several orbits. Sir Isaac shows that there is no common place such as that conjectured by Plato, provided the gravitating power of the sun remains constant; but that Plato's affirmation is true if we suppose the gravitating power of the sun to be doubled at that moment of time when they all arrive at their several orbits. "If we suppose," says he, "the gravity of all the planets towards the sun to be of such a quan tity as it really is, and that the motions of the planets are turned upwards, every planet will ascend to twice its height from the sun. Saturn will ascend till he be twice as high from the sun as he is at present, and no higher; Jupiter will ascend as

high again as at present, that is, a little above the orb of Saturn; Mercury will ascend to twice his present height, that is, to the orb of Venus; and so of the rest; and then, by falling down again from the places to which they ascended, they will arise again at their several orbs with the same velocities they had at first, and with which they now revolve.

"But if so soon as their motions by which they revolve are turned upwards, the gravitating power of the sun, by which their ascent is perpetually retarded, be diminished by one-half, they will now ascend perpetually, and all of them, at all equal distances from the sun, will be equally swift. Mercury, when he arrives at the orb of Venus, will be as swift as Venus; and he and Venus, when they arrive at the orb of the earth, will be as swift as the earth; and so of the rest. If they begin all of them to ascend at once, and ascend in the same line, they, will constantly, in ascending, become nearer and nearer together, and their motions will constantly approach to an equality, and become at length slower than any motion assignable. Suppose, therefore, that they ascended till they were almost contiguous, and their motions inconsiderably little, and that all their motions were at the same moment of time turned back again, or, which comes almost to the same thing, that they were only deprived of their motions, and let fall at that time, they would all at once arrive at their several orbs, each with the ve locity it had at first; and if their motions were then turned sideways, and at the same time the gravitating power of the sun doubled, that it might be strong enough to retain them in their orbs, they would revolve in them as before their ascent. But if the gravitating power of the sun was not doubled, they would go away from their orbs into the highest heavens in parabolical lines.”*

"These things," says he, "follow from my Princip. Math. lib. i. prop. 33, 34, 35, 36."