Dunno if it's true, but it's fascinating.
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.
http://www.mathematicsmagazine.com/Articles/NicolaTesla.php#...
“Tesla’s physics requires a quite different understanding of mathematics, in some extent it is sacral in the spirit of Pythagoras. Pythagoras considered that numbers and subjects are interrelated. They correspond to each other in property due to informational and mathematical aspects of matter existing as one of the manifestations of the Divine Logos.”
Not totally sure how to interpret that…