Page:BoscovichSpaceTime.djvu/6

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 * perfectly free mass will permeate through any other mass, without there being any danger of a collision of one point with another. Here there would be an apparent compenetration similar to the penetration of light through crystals, oils through wood, & marble, without any real compenetration of the points. In denser masses, & those endowed with a smaller velocity, the repulsive forces for the most part prevent further motion without any impact; & this also excludes sensible as well as apparent compenetration. In very tenuous masses moving with very great velocities, as rays of light propagated through homogeneous substances, or through other rays, the very slight inequality of the actions, derived from the unequal distances of the circumjacent points, will be prevented by the high velocity; & perfectly free progress will take place in all directions without any danger of collisions. This removes altogether the greatest & only real difficulty in the idea of the propagation of light by means of a substance that is emitted & travels forward. But I have now said quite enough upon this matter.
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