Are you familiar with that little half height floor in Being John Malkovich? You are pretty much there, but for the internet. In all seriousness, interesting article. Quoting you, quoting Newton: I don't think we can point to anything unlike this, correct?: up/down are sensations of gravity, temperature is a sensation of molecular motion, etc. Random thought: I can't think of any sensations that result from multiple physical phenomenon. Color and intensity, frequency and amplitude, perhaps... but nor from 'green and hot' or 'down and loud'. I wonder if any intelligence combines two unique phenomenon into a useful sensation.No, not a lurker, in fact I'm not really sure where I am yet!
Newton also said something very strange: he said that "the rays to speak properly are not coloured". By this he meant that a colour is really a sensation of the mind resulting from light, just like a sound is a sensation of the mind resulting from physical vibrations of the air.
Well, that's very exciting! Perhaps length would be at the objective extreme, but even there we at least sometimes need to make a distinction between physical and perceived length, for example in the T illusion. I see the gap between spectral distribution and colour as being at the other extreme, in that there are two gaps of subjectivity involved. With just three cone cell types we can't know the spectral distribution of a light, only some limited qualities of it (dominant wavelength and purity as defined by an opponent visual system), so many different spectral distributions look identical to us. And then these limited qualities that we do detect are tagged for us with entirely subjective experiences whose relationships have no basis in the linear spectrum. In between you have perceptions that correlate more directly (if non-linearly) with the physical stimulus, such as sound and vibration rate, or warmth and molecular motion.