Scientist Valentino Braitenberg sadly passed away a few days ago. His most public accomplishment was perhaps his book "Vehicles", where he imagined small toy vehicles on a tabletop to show how seemingly purposeful and deliberative behaviours can arise from very simple and easy to understand mechanisms.
This book introduces the idea of embodied cognition — thought processes and behaviour don't occur in isolation; they are a product of the interaction between the agent and the environment. It means, for instance, that a simple agent in its native environment will be able to do much more, and better than its own internal design could really do alone. It also means that an organism is locked to a certain range of environment and will do much worse than its true capabilities.
My favourite example is water beetles that lay their eggs in puddles and shallow ponds. The female flies around looking for a body of water, and then dives straight down into it, where it lays its eggs. Finding water from above like that would seem to be pretty complicated. In reality it merely looks for a patch of ground with strongly polarized light — like many insects their eyes have cells sensitive to the polarization — and dives into it. Complex behaviour with very little thought. Of course, today our world is full of large, strongly polarized surfaces such as car hoods and building roofs and the beetles dive right into them instead, with messy results. Behaviour that looks complex and adaptive in one situation can quickly become maladaptive when the environment changes.
This book matters to me personally too. I first read it as a teenager — it is written for laymen and really an easy, relaxing read — and it is one of the books that steered me toward science and toward my current interests of neuroscience and robotics. I know it has had a similarly huge impact on many of my friends and colleagues. I'm truly sad to hear he is gone.
Edit: Valentino Braitenberg, not "Emilio". Duh. No idea where I got "Emilio" from.