1. René Descartes made a profound observation: 'I think, therefore I am.'
2. The fact we think, he argued, proves we exist; the rest can be doubted.
3. Descartes used the act of seeing as a way to illustrate his point of view.
4. He sketched a diagram showing how vision might work mathematically.
5. He showed light entering the eye as rays of lines that converge at the back.
6. But this wasn't seeing, observed Descartes, rather, the work of judgement.
7. In the sense that we see what’s there, then come to a decision about what it is.
8. From this concept of vision, seeing becomes a metaphor for the role of a judge.
9. And just as a judge decides based on the evidence, seeing is based on evidence.
10. In doing so, Descartes revealed the importance of seeing as active observation.
11. Meanwhile, science learned to separate biological sight from cultural judgement.
12. Biological sight: what there is to see; cultural judgement: how we make sense of it.
13. So seeing the world isn’t about how we see things, but what we make of what we see.
14. Ludwig Wittgenstein's duck–rabbit drawing is a helpful way to picture the difference.
15. It can look like a duck or a rabbit, depending on how your mind decides to see it.
16. This ambiguity arises because the brain runs two streams: one for perception, one for action.
17. And what we make of what we see is shaped by the interaction between the two streams.
18. As art theorist Nicholas Mirzoeff puts it, the brain isn't a camera, but a sketch pad.
19. So seeing doesn't just happen, it's something we do; it takes brains, not just eyes.