Science is not limited to the so-called scientific world. It reaches beyond all classes, it belongs to the full depth and width of life. Science belongs to thinking humanity in its entirety. And so it is with the separation of matter and force. Only a stultified fanaticism can ignore the practical distinction. The miser who accumulates money without adding any wealth to his life process forgets that the valuable element of money resides in its force, which is different from, its substance. He forgets that not mere wealth as such, not the paltry gold substance, lends a reasonableness to the quest for its possession, but its spiritual content, its inherent exchange value, which buys the necessities of life. Every scientific practice, which means every action carried on with a predetermined success and with understood substances, proves that the separation of matter and force, though only performed in thought and existing in thought, is nevertheless not an empty phrase, not a mere hypothesis, but a very fertile idea. A farmer manuring his field is handling "pure" manuring force, in so far as it is immaterial for the abstract conception whether he is handling cow dung, bone dust, or guano. And in weighing bundles of merchandise, it is not the iron, copper, stone, etc., which is handled by the pound, but their gravity. True, there is no force without matter, no matter without force. Forceless matter and matterless force are nonentities. If idealist naturalists believe in an immaterial existence of forces which, so to say, carry on their goblin-pranks in matter, forces which we cannot see, cannot perceive by the senses and yet are asked to believe in, then we say that such men are to that extent that naturists, but mere speculators, in other words spiritualists. And the word of the materialists who refer to the intellectual separation of matter and force as a mere hypothesis, is quite as brainless.