Here's an example of the gather node: No lights, it's all lit by a glowing plane above the whole scene. The figure and the ground both have the gather node in their shaders, plugged in the alternate_diffuse input. The gather node uses lots of raytracing to gather the color/illumination of surrounding geometry - somewhat similar to C4D's "stochastic radiosity". In geek language, it's called "unbiased single bounce monte carlo path tracing".