p^ Human Physiology. 



bodies floating on the water are drawn together by a mutual 

 attraction. Sticks on a pond gather in a mass. A leaden 

 weight let down by a string from the top of a precipice is 

 drawn toward the rock. The constant pull of the earth keeps 

 all pendulums swinging. The facts of gravitation are in every 

 moment's experience the cause or mode of action is utterly 

 inscrutable. 



But if I take a bit of loadstone, or magnetic iron ore, or a 

 piece of steel which has become magnetic, I see the action of a 

 similar force. Pieces of iron move toward it from short 

 distances, and cling to it with great tenacity. Holding it 

 under a sheet of paper on which I have sprinkled iron sand, or 

 filings, I see them drawn to it, arranging themselves in regular 

 forms, and even rising, one upon another, like crystals or 

 vegetable growths. The action of a force is evident. I can 

 trace the curves in which it moves; but how one mass of 

 matter can so act upon other masses, even through intervening 

 substances, I cannot imagine. The earth is a magnet, held 

 with its north pole always pointing to one spot in the heavens, 

 as it goes spinning on its axis round the sun and drawing all 

 things to itself. The sun is a huge magnet, held in its own 

 place by immense forces, and holding all its planets, from 

 Vulcan 14,000,000 miles, to Neptune 2,746,271,000 miles 

 distant How can we conceive of bodies of matter attracting 

 each other at such distances? 



It may be that all forms of matter are modifications of one 

 form, if indeed matter be not itself a form of force; and that 

 all forms of force, energy, and motion, are modifications of one 

 force, one infinite energy and power. Sunshine seems to be 

 transformed into the vital -force and stored up energy of great 

 forests and deposits of coal. These, in turn, warm our houses, 

 smelt our ores, feed our furnaces, drive our steam engines, 

 propel steamers and locomotives. It is sunshine which pro- 

 duces cotton, and then transports it, and spins and weaves it 



