Refraction is the directional change of a wave as it passes through one medium to another. The most common and easily observed is light--when it passes through rain droplets in the air to form a rainbow or through bubbles in little, self-contained hodgepodges of colour.
Refraction is based on how light changes when it bends. There are three major sections, each examining a different medium. The first section envisions light passing through bubbles as they float, zip, and pop in the air. Infinetisimal, impermanent little rainbows that, at once, scurry and laze through space before they stretch to their breaking point.
The central section follows rays of light as they hit a body of water. Immediately slowing and bending downward, they slowly dissipate as the depths swallow them up.
The final section is a prism, a rainbow of colour and a union of seemingly disparate elements. Light angles upward when it enters a prism and then, spectacularly, separates into seven visible shades.