# Any scientific basis behind Thoreau's Stacked Shadows?

In Walden Henry David Thoreau states,

Sometimes, when the ice was covered with shallow puddles, I saw a double shadow of myself, one standing on the head of the other, one on the ice, the other on the trees or hillside.

This was in a section where Thoreau was simply surveying the pond and describing things matter-of-factly, so I don't think it is meant to come across as symbolism.

I was hoping to find a possible explanation for this. Since he mentions this to happen only when shallow puddles are present, Perhaps it's a combination of reflection and refraction?

## 1 Answer

Interesting question!

Consider the sketch below. Imagine that the ice is covered completely by water, making the surface reflective. If Thoreau is standing on the ice, the sunlight blocked by his body will form a shadow on the surface of the water.

From the locations on the ice, where his shadow is present, light will NOT be reflected on to the steep hillside in front of him. Therefore, there will be a Thoreau-shaped region on the hillside, where less light arrives - a secondary shadow!

As can be seen, Thoreau will observe two shadows seemingly "standing" on top of each other - one on the water and the other on the hillside.

EDIT: Looks like I was a bit to quick posting this drawing. The secondary shadow on the wall will actually be upside down!

• Wouldn't the 2nd shadow be upside down in this situation? Feb 5, 2020 at 14:33
• Gosh, I think you might be right! Feb 5, 2020 at 20:37
• I was thinking what Bradley said as well. Something that made me question the precision of the word "standing" would be that the sharpness of the shadow should be reduced not only by the distance between Thoreau and the trees/hillside but also the fact that the reflection would experience some diffusion, right? So I'm skeptical whether a sharp enough shadow can be perceived to determine it's orientation (upside down or right side up). Feb 6, 2020 at 2:03