Now if light be reflected, not by impinging on the solid parts of bodies, but by some other principle; it's probable that as many of its rays as impinge on the solid parts of bodies are not reflected but stifled and lost in the bodies. For otherwise we must allow two sorts of reflexions. Should all the rays be reflected which impinge on the internal parts of clear water or crystal, those substances would rather have a cloudy colour than a clear transparency. To make bodies look black, it's necessary that many rays be stopp'd, retained, and lost in them; and it seems not probable that any rays can be stopp'd and stifled in them which do not impinge on their parts.

Isaac Newton

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