The concepts and theories of modern physics / By J.B. Stallo.

  • John Stallo
Date:
1900
Catalogue details

Licence: In copyright

Credit: The concepts and theories of modern physics / By J.B. Stallo. Source: Wellcome Collection.

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    ence of such things. I answer that, according to any test we have of possibility, they are not even possible. Their existence, so far as we can form any judgment, would seem to be inconsistent with the physical consti- tution of our planet at least, if not of the universe. To get rid of this difficulty, and at the same time to save the credit of the supposed system of necessary truth, it is customary to say that the points, lines, circles, and squares which are the subject of geometry exist in our conceptions merely, and are part of our minds; which minds, by working on their own materials, construct an a jpriori science,-the evidence of which is purely men- tal, and has nothing whatever to do with outward ex- pci-ience. By however high authorities this doctrine may have been sanctioned, it appears to me psychologi- cally incorrect. The points, lines, circles, and squares which anyone has in his mind are (I apprehend) simply copies of the points, lines, circles, and squares which he has known in his experience. Our idea of a point I apprehend to be simply our idea of the minimum visi- hile, the smallest portion of surface which we can see. A line, as defined by geometers, is wholly inconceivable. We can reason about a line as if it had no breadth; be- cause we have a power, when a perception is present to our senses, ora conception to our intellects, of attending to a part only of that perception or conception, instead of the whole. But we can not conceive a line without breadth ; we can form no mental picture of such a line ; all the lines which we have in our minds are lines ])osse.ssing breadth. If any one doubts this, we may re- fer him to his own experience. I much question if any one, who fancies that he can conceive what is called a mathematical line, thinks so from the evidenoe of his consciousness: I suspect it is rather because he supposes