The exact quotes from Nikola Tesla’s own autobiography are: I started by first picturing in my mind a direct-current machine, running it and following the chan

The exact quotes from Nikola Tesla’s own autobiography are: I started by first picturing in my mind a direct-current machine, running it and following the changing flow of the currents in the armature. Then I would imagine an alternator and investigate the processes taking place in a similar manner. Next I would visualize systems comprising motors and generators and operate them in various ways. The images I saw were to me perfectly real and tangible. […] The images I saw were wonderfully sharp and clear and had the solidity of metal and stone, so much so that I told him: “See my motor here; watch me reverse it.” […] The pieces of apparatus I conceived were to me absolutely real and tangible in every detail, even to the minute marks and signs of wear. I delighted in imagining the motors constantly running, for in this way they presented to mind’s eye a more fascinating sight.