[I have said that I want to post more often; but I don't want to overburden the blog with too much substance. Thus I am trying out a light feature to be run each week besides the Friday post: a short Tuesday "nondefinition".]
Brain. An appliance invented by nineteenth-century German philosophers to remove the drudgery from thought experiments. Pity the situation of the old Arabic philosophers who had ask God to specially create a flying man—separated from all his parts, falling forever through lightless infinity—merely in order to raise the problems which any modern philosopher can confront by borrowing a mad scientist's brain in a vat.