Principles Of Human Knowledge - pg. 127

Hence it is evident, that those things which under the notion of a cause co-operating or concurring to the production of effects, are altogether inexplicable, and run us into great absurdities, may be very naturally explained, and have a proper and obvious use assigned them, when they are considered only as marks or signs for our information. And it is the searching after, and endeavouring to understand those signs instituted by the Author of Nature, that ought to be employment of the natural philosopher, and not the pretending to explaing things by corporeal causes ; which doctrine seems to have too much estranged the minds of men from that active principle, that supreme and wise spirit, in whom we live, move, and have our being.