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Satirical writings also, such as Juvenal, and Persius, and above all Horace; though they paint the deformities of men, yet they thereby teach us to know them.

There is another use of reading, which is for diversion and delight. Such are poetical writings, especially dramatic, if they be free from profaneness, obscenity, and what corrupts good manners; for such pitch should not be handled.

Of all the books of fiction, I know none that equals Cervantes's History of Don Quixote in usefulness, pleasantry, and a constant decorum. And indeed no writings can be pleasant, which have not nature at the bottom, and are not drawn after her copy.

There is another sort of books, which I had almost forgot, with which a gentleman's study ought to be well furnished, viz. dictionaries of all kinds. For the Latin tongue, Littleton, Cooper, Calepin, and Robert Stephens's Thesaurus Linguæ Latinæ, and Vossii Etymologicum Linguæ Latinæ; Skinner's Lexicon Etymologicum is an excellent one of that kind, for the English tongue. Cowel's Interpreter is useful for the

law terms. Spelman's Glossary is a very useful and learned book. And Selden's Titles of Honour a gentleman should not be without. Baudrand hath a very good Geographical Dictionary. And there are several historical ones, which are of use; as Lloyd's, Hoffman's, Moreri's. And Bayle's incomparable dictionary is something of the same kind. He that hath occasion to look into books written in Latin since the decay of the Roman empire, and the purity of the Latin tongue, cannot be well without Du Cange's Glossarium mediæ et infimæ Latinitatis.

Among the books above set down, I mentioned Vossius's Etymologicum Linguæ Latinæ; all his works are lately printed in Holland in six tomes. They are fit books for a gentleman's library, containing very learned discourses concerning all the sciences.

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E L E M E N T S

OF

NATURAL PHILOSOPH Y.

CHAPTER I.

Of Matter and Motion,

MATTER is an extended solid substance; which being comprehended under distinct surfaces, makes so many particular distinct bodies.

Motion is so well known by the sight and touch, that to use words to give a clear idea of it would be in vain.

Matter, or body, is indifferent to motion, or rest.

There is as much force required to put a body, which is in motion, at rest, as there is to set a body, which is at rest, into motion.

No parcel of matter can give itself either motion or rest, and therefore a body at rest will remain so eternally, except some external cause puts it in motion; and a body in motion will move eternally, unless some external cause stops it.

A body in motion will always move on in a straight line, unless it be turned out of it by some external cause ; because a body can no more alter the determination of its motion, than it can begin it, alter, or stop its motion itself.

The swiftness of motion is measured by distance of place, and length of time wherein it is performed. For instance, if A and B, bodies of equal or different bigness, move each of them an inch in the same time; their motions are equally swift; but if A moves two inches, in the time whilst B is moving one inch, the motion of A is twice as swift as that of B.

The quantity of motion is measured by the swiftness of the motion, and the quantity of the matter moved, taken together. For instance, if A, a body equal to B, moves as swift as B; then it hath an equal quantity of motion. If A hath twice as much matter as B, and moves equally as swift, it hath double the quantity of motion; and so in proportion.

It appears, as far as human observation reaches, to be a settled law of nature, that all bodies have a tendency, attraction, or gravitation towards one another.

The same force, applied to two different bodies, produces always the same quantity of motion in each of them. For instance, let a boat, which with its lading is one ton, be tied at a distance to another vessel, which with its lading is twenty-six tons; if the rope that ties them together be pulled, either in the less or bigger of these vessels, the less of the two, in their approach one to another, will move twenty-six feet, while the other moves but one foot.

Wherefore the quantity of matter in the earth being twenty-six times more than in the moon; the motion in the moon towards the earth, by the common force of attraction, by which they are impelled towards one another, will be twenty-six times as fast as in the earth; that is, the moon will move twenty-six miles towards the earth, for every mile the earth moves towards the moon.

Hence it is, that, in this natural tendency of bodies towards one another, that in the lesser is considered as gravitation, and that in the bigger as attraction ; because the motion of the lesser body (by reason of its much greater swiftness) is alone taken notice of.

This attraction is the strongest, the nearer the attracting bodies are to each other; and, in different distances of the same bodies, is reciprocally in the

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