An example of an indirect light

On the top you see a big reflection of the Sun off my not very polished wooden floor.   On the bottom is the view in the opposite direction.   Three interesting points:

1. The secondary light effect is surprisingly (to me) strong and un-diffused.
2. The secondary light effect is achromatic even through it is off a brown floor-- the specular component is achromatic.
3. Note the tertiary effect on the wall by the picture frame.    This would be tough for most renderers.