There was a failure to recognize the deep problems in AI; for instance, those captured in Blocks World. The people building physical robots learned nothing.
You don't understand anything until you learn it more than one way.
The brain happens to be a meat machine.
Anyone could learn Lisp in one day, except that if they already knew Fortran, it would take three days.
We turn to quantities when we can't compare the qualities of things.
Speed is what distinguishes intelligence. No bird discovers how to fly: evolution used a trillion bird-years to 'discover' that – where merely hundreds of person-years sufficed.