Dogen assumes the relative viewpoint in the next sentence of Genjo Koan:

When the moon is reflected in water, the moon does not get wet and the water is not disturbed. Though the light of the moon is wide and great, it is reflected in a foot or an inch of water. The whole moon and the whole sky are reflected in a single dewdrop on a blade of grass. 

He then compares this observation with a statement that transcends the relative and the absolute:

Potential does not annihilate the individual, just as the moon does not disturb the water. The individual does not hinder potential, just as a dewdrop does not hinder the sky and moon. 

And then he wraps the paragraph up with the practical:

The depth of potential may be as high as the moon. We can experience its duration with our body and mind, and observe its breadth the sky and the moon.