# 25.2 FRAME-ARRAYS
When we first discussed how Builder works, we assumed that it employed a vision-agent, See, to locate the various blocks it needs. However, we never discussed how See itself might work. A person simply "looks and sees" — but that's more complicated than it seems. For instance, even a simple cube looks different from each point of view, since as you move, the images it makes inside your eye keep changing in both shape and size.

Frame-Arrays. When we move, our vision-systems switch among a family of different frames that all use the same terminals.

I do not mean to suggest that every time you see a new object you build a brand-new frame-array for it. First, you try to match what you see to the frame-arrays in the memories you have accumulated and refined over periods of many years. How do frame-arrays originate? I would assume that this underlying pattern — of families of frames that all share common terminals — is built into the architectures of major sections of the brain. But although that pattern is "built in," developing the skills for using it involves each child in more than a decade of predestined learning.