Week 8: We've All Done It

We've all done the flash light behind the flesh, ET phone home, trick at some point or another behind our fingers. And of course, where there is less mass of flesh and bones, your skin is far more transparent and allows more light to pass through. The three pictures above are my hand with a flashlight behind it, as the flashlight moves deeper into my hand. What is fascinating to me about it is not the fact that light passes through as the colour red, though that is cool that human flesh can compare to a gel with its pigment, but the fact that human flesh is thin enough, transparent enough, to allow light to pass through, even at the center of your palm where your hand is almost at its thickest. Sure, skin allows liquids to pass through (outwards), but prevents the inward acceptance of liquids. Why is it the complete opposite with light that it can be accepted by human flesh, but not emanate or create it otherwise?
And certain objects that do accept liquids and retain water as given, such as wooden blocks or duvetine, do not allow light to pass through its solidity at all. Baffling.