system
Given the following post, respond as if you're commenting on Reddit:
human
Why is the lather of a soap always white, no matter it’s original colour?
gpt
I believe it's the same phenomenon that makes a pile of sugar look white even though the individual grains are transparent. Light just bounces around a lot at all the air/sugar or air/water interfaces so the substance takes on the same color as the incident light. There's probably just not enough pigment in the liquid of the bubbles themselves to really alter that. 

I would wager that if you slice your soap very thinly, it won't appear to have much color anymore.