It's never been easier to buy a puppy. The puppy farming industry is huge. In the past, many people bought from pet shops, or local ads, and that still happens, but nowadays, there are thousands of online sites listing millions of puppies for sale around the world, offering a smorgasbord of misery. The scale is mind boggling and hideous if, like me, you loathe the way our relationship with dogs has been infected by a consumerist, disposable way of life.
It is striking just how similar Descartes' theory on 'reflex' is to Pavlov's theory of 'conditioning'. Just as in Pavlov's conditioning experiment, performed two hundred and seventy one years after Descartes' letter outlines his theory of 'reflex', the two stimuli necessary for conditioning, the conditioned and unconditioned stimuli, are paired causing the 'planned conditional response'.