the earth. For close and strict compaction of matter induces a disposition towards motion torpid and averse; as on the other hand free explication of it induces a disposition prompt and apt. Nor was it ill done by Telesius (who revived the philosophy and discussions of Parmenides in his book on the original source of cold) to introduce into nature, not indeed coessentiality and conjugation (which he would have), but yet affinity and conspiration; making heat, light, tenuity, and mobility to be allied on one part; cold, darkness, density, and immobility on the opposite; and placing the seat of the first set in the heaven, of the second in the earth. But if rest and immobility be admitted, it seems that motion without limit and perfect mobility should likewise be admitted, especially in opposite natures. Now this motion is the motion of rotation, such as is generally found in the celestial bodies. For motion in a circle has no limit, and seems to proceed from an appetite of the body, which moves merely for the sake of moving and following itself and seeking its own embraces, and exciting and enjoying its own nature, and performing its own operation; whereas contrariwise motion in a straight line seems like a journey to an end, as seeking both to reach the limit where it may cease and rest, and to attain some object and then discontinue its motion. We must see therefore how this motion of rotation, which is the true and perennial motion, and commonly considered peculiar to the heavenly bodies, acquits itself, and by what control it spurs and bridles itself, and generally how it is affected; in the explanation of which things I shall not stand upon that piece of mathematical elegance, the reduction of motions to perfect circles, either eccentric or concentric, or that high speech, that the earth in comparison to heaven is a point and not a quantity, or many other fictitious inventions of astronomers; but remit them to calculations and tables. But first I will make a division of the motions of the heavenly bodies. Some are cosmical, others mutual. Those I call cosmical, which celestial bodies assume by consent, not only of the heavens, but likewise of the universe; those mutual, in which one celestial body depends on another. And this is a true and necessary division. The earth then being stationary (for that I now think the truer opinion), it is manifest that the heaven revolves in a diurnal motion, the measure whereof is the space of twenty-four hours or thereabouts, the direction from east to west, the axis of

revolution certain points (which they call poles) north and south. For the heavens do not travel on movable poles, nor are there any other points than those I have mentioned. And this motion appears to be truly cosmical, and therefore one and the same; except in so far as it admits both diminutions and deviations; according to which diminutions and deviations this motion strikes through the whole universe of things movable, and penetrates from the starry heaven to the bowels and depths of the earth; not forcing them along with violence or vexation, but by a perpetual consent. And this motion is in the starry heaven perfect and entire, as well in just measure of time, as in exact restitution of place. But the lower down we come, the more imperfect is this motion, in respect of slowness, and in respect likewise of deviation from circular motion. And first I must speak of the slowness separately. I say then that the diurnal motion of Saturn is too slow to allow of its completing the circle or coming back to the same place within twenty-four hours; but that the starry heaven moves faster, and outstrips Saturn each day by a distance which multiplied by the number of days in thirty years makes up the whole circuit of the heaven. So also with regard to the other planets, according to the diversity of their several periods; so that the diurnal motion of the starry heaven (speaking of the period only, without reference to the magnitude of the circle) is about one hour quicker than the diurnal motion of the moon. For if the moon completed its course in twenty-four days, it would be quicker by an hour exactly. Therefore that motion of opposition and resistance from west to east which they talk of, and which is attributed to the planets as peculiar to them, is not a real motion, but only in appearance, owing to the starry heaven advancing faster to the west, and so leaving the planets behind towards the east. Upon which supposition, it is manifest that the velocity of this cosmical motion decreases in regular order as it descends, so that the nearer every planet approaches the earth the slower it moves; whereas the received opinion disturbs and inverts the order; and by attributing a peculiar motion to the planets falls into the absurdity of supposing that the nearer the planets approach the earth (which is the seat of immobility) the quicker they move; a thing which astronomers idly and unsuccessfully endeavour to account for by supposing a remission of the violence of the primum mobile. And if it seem strange

that in so great a space as lies between the starry heaven and the moon this motion diminishes so little; namely less than one hour, which is a twenty-fourth part of the diurnal motion; it is to be remembered that the nearer a planet is to the earth the smaller is the circle of its revolution; so that if we add the decrease in the magnitude of the circle to the decrease in the time of revolution, we shall see that the motion is diminished very considerably. Thus far I have spoken of velocity separately; as if the planets (placed, for instance, under the equinoctial, or any of the parallels) were only outrun by the starry heaven and by one another, but yet in the same circle. For this would be simple leaving behind without obliquity of motion. But it is manifest that the planets not only move with unequal velocity, but do not return to the same point of the circle, deflecting to the north and south; the limits of which deflexion are the tropics; and to this deflexion it is that we owe the Oblique Circle and the Difference of Polarity; just as we owe to the inequality of velocity the motion of Resistance. But the nature of things does not stand in need of this device, more than of the other; seeing that by adopting spiral lines (the supposition which comes nearest to the sense and the fact) the thing is accomplished, and those phenomena are saved. And (which is the chief point) these spirals are nothing else than defections from perfect circular motion, whereof the planets are impatient. For in proportion as substances degenerate in purity and freedom of development, so do their motions degenerate. Now it happens, that as in point of velocity the higher planets move faster, and the lower less fast; so also the higher planets make spirals more closely coincident and coming nearer to circles, the lower make spirals more disjoined and further apart. For continually as they descend they recede more and more both from that height of velocity and that perfection of circular motion, in regular order. Yet in this the planets agree (as being bodies that retain much of a common nature, though otherwise differing) that they have the same limits of deflexion. For neither does Saturn come back within the tropics, nor the moon go forth beyond the tropics (and yet with regard to the wandering of Venus there are certain traditions and observations not to be overlooked); but all the planets, whether the higher or lower, as soon as they reach the tropics, turn back and retrace their course, disliking the smaller spiral in which they

would have to move if they approached nearer the poles; and shrinking from that loss of motion, as from the destruction of their nature. For however in the starry heaven both the stars near the poles and the stars about the equinoctial maintain their ranks and stations, one being kept in order by another, with a perfect and equable constancy; yet the planets seem to be of such a mixed nature as not willingly to endure either a shorter circle or a larger. These views then concerning the celestial motions appear to me a little better than the carrying by force, the repugnance of motions, the different polarity of the zodiac, the inverted order of velocity, and the like; which have no manner of agreement with the nature of things, however they keep peace, such as it is, with the calculations. Neither were the better astronomers blind to these things; but being intent on their art, and foolishly attached to perfect circles, and catching at subtleties, and too servile to philosophy, they scorned to follow nature. But this imperious disposition of philosophers towards nature is worse even than the simplicity and credulity of the vulgar; if a man disdains a plain thing because it is plain. And yet a vast evil it is and of very wide extent, that the human wit, not being able to match nature, must needs put itself above nature. But now we must inquire whether that single and simple motion, in a circle and spiral, from east to west, on certain poles south and north, ends and terminates with the heaven, or extends likewise to things below. For it will not be open to us to invent here in the regions next us such things as they suppose in the heavens. If therefore in these regions also this motion be found, it will appear that in heaven likewise it is, under the conditions of a common or cosmical nature, such as we experience it. First then it is plain that it is not confined within the limits of heaven. But the demonstrations and evidences on this point I have fully treated in my "anticipation" concerning the ebb and flow of the sea'; to which men are therefore referred; and taking this for settled and concluded, I will proceed to the other motions of celestial bodies. These I have said are not cosmical, but mutual, or having relation one to another. There are four kinds of motions visible in heavenly bodies besides that which I have called cosmical, which is the diurnal motion

See p. 449. of this volume.

by spirals within the tropics. For the stars either rise higher and again sink lower, so as to be further off and nearer the earth; or they turn and wind from side to side of the zodiac, running out more to the south or more to the north, and forming what they call dragons; or they vary in velocity and likewise in direction of motion (for I put these two together), proceeding sometimes quicker, sometimes slower, sometimes in progression, sometimes in regression,sometimes likewise stopping and remaining stationary; or they are attached and circumscribed at a greater or less distance from the sun. The causes and natures of these motions I will only give in general and by heads; for this the plan of my work here demands. But to pave and open the way for this, I must say without reserve what I think with regard to certain philosophical doctrines, as well as astronomical hypotheses, and likewise with regard to the observations of astronomers in various ages, upon which they build their art; all which appear to me full of error and confusion. There are some axioms then, or rather opinions, which being received by philosophers, transferred into astronomy, and unhappily believed, have corrupted the art. Of these my rejection and judgment will be simple: for I have no time to spend in confutations. The first is, that all things above the moon inclusive are incorruptible, and not subject to new generations or changes of any kind. Of this I have spoken elsewhere, as being a superstition and a vanity. But it is the fountain from which springs that vast evil, that upon every anomaly astronomers frame new and (as they think) corrected theories, and often apply to things that are as it were fortuitous causes eternal and invariable. The second is, that the heaven (as consisting of a fifth essence, and of no elementary substance) admits not of those turbulent actions of compression, relaxation, repulsion, submission, and the like, that seem to be produced by a certain hardness and softness of bodies, which are regarded as elementary qualities. But this assertion is an insolent and licentious repudiation of fact and sense. For wherever a natural body is placed, there also is resistance, and that in proportion to the body. And wherever there are natural bodies and local motion, there is either repulsion, or yielding, or division; for these things above mentioned, namely, compression, relaxation, repulsion, yielding, with many others, are universal passions of matter every