There is a curious observation in Lactantius, which belongs properly to this subject. Among other arguments to shew the superiority of man in the creation, and the immortality of his nature, he produces this; that of all the creatures known to us, man is the only one that has the use and command of .the element of fire. He is familiar with that heavenly substance, without which there is neither light nor life, while the most powerful and ferocious of beasts are alarmed by it, and fly from it. He is intrusted with a power most like to that of God himself, who has the direction of all the elements; and therefore he has a privilege which distinguishes him, and sets him above all the creation, and gives him an alliance with the divine nature. How dreadful would it have been, if brute creatures had been intrusted with the same liberty! if there had been the use of fire, where there is not the use of reason! What would Lactantius have said, if he had been witness to the present state of philosophy, when we have obtained the art of using and directing the force of fire, independent of its heat, as the great cause of motion in the world?-of even drawing it down from the clouds of heaven, and di verting verting (as we seem to do) the stroke of lightning itself? Instead of being puffed up with pride and insolence, let us regard this rather as a gift of Providence, than a discovery of human wit: let us, in the words. of the Scripture, glorify God, who (for some wise and good end) hath given such power unto men: and let us make a wise and devout use of it. The most ancient heathen philosophers, when they contemplated this wonderful privilege of man, in enjoying the use and dominion of the element of fire, that walexv wugos σedas*, like to God himself, persuaded themselves that as it was a privilege too great for man's estate in the world, it was originally stolen from heaven; and that this very theft was the crime which brought all manner of evil into the world. I have frequently wondered at this doctrine, which is plainly taken from the Mosaic history, where the original crime consisted in a desire of being equal * Пavlexve wugos reλas-the brightness of fire, the uni versal artificer: this expression is very strong and beautiful, and is taken from the Prometheus of Eschylus, the plot of which is founded entirely on this supposed theft of fire, the crime that made the propitiatory sufferings of Prometheus necessary. equal to God: the heathens interpreted that desire to consist in aspiring to the familiar use of fire, and stealing it from heaven for that purpose. They could not see how we are so much like gods in any other respect. 391 DISCOURSE V. On Air, Sound, Music, &c. AIR may properly be called a fluid, be cause its parts move freely among themselves, so that it flows like other liquids, and follows the general laws of hydrostatics; but it has some peculiar properties which distinguish it from other fluids, particularly its compressibility and elasticity. The air is hard to be understood by an experimental analysis, on account of the subtilty of its parts, and the heterogeneous matter which is mixed with it. In the air of the atmosphere, which we commonly breathe, we have a compound, which contains diffused in it a subtile vapour from the waters of the earth and clouds, and with this, all such parts from earthy substances as are volatile; as the parts of sulphurs, volatile oils, volatile salts, and even earths, minerals, and metals, when greatly refined and subtilized. The various parts which enter into this compound CC 4 compound fluid of the atmosphere, have perplexed the subject to such a degree, with those who have undertaken to study the nature of the air, that some have supposed air to be nothing but water rarefied, others nothing but salt of some kind in another form, Thus we might dispute about wine, beer, and spirits, till we had lost sight of the element of water; but here we are in less danger, because water is a grosser fluid, and more obvious in its simple form. When all other parts are removed which enter into the composition of the atmosphere, there certainly remains a fluid, which is the vehicle and substratum of them all; insomuch, that if there were neither earth, nor salt, nor oil, nor sulphur, nor water, still there would be that air which gives motion to the lungs, and is the spring of animal life. simple fluid is the first object of inquiry to those who consider the nature of the air; and the properties of air, which arise from the mixture of other things with it, are to be regarded rather as accidents than properties. This But when we have done all we can to reduce air to its native simplicity, still it is a compound; for the air in which we move, and |