Wikipedia has a nice article on Venture Capital. It seems to suggest a second source of seed capital that it doesn't call out explicitly, e.g. the government, especially during extraordinary times such as WWII. The military had to create industries and suppliers from scratch to meet its needs in major defense projects. Think about the creation of atomic weapons, and all of the various components and materials that had to be created from out of the blue. General Leslie Groves was effectively a venture capitalist with a bottomless Limited Partner in Washington.
Wikipedia credits General Georges Doriot as the father of modern venture capital. My guess is that he got the idea from his experience in the wartime years, where the audacity of the military meant starting things from scratch under duress. Doriot was clearly a well versed business professor, having taught at the Harvard Business School, but I’m guessing it took the audacity of war to break through to the idea that you could start a company entirely from scratch, and do this as a repeatable business.
So we begin with wealth, expansive thinking, audacity. This is an angel dominated world. Wealthy people spending their money to make them more money and expanding their legacy. But in my mind, modern venture capital begins when you have professionals investing other people’s money. This seems to first happen with Venrock Associates, which starts as a group of professionals investing the Rockefeller fortune. Laurance Rockefeller starts it off, but he quickly hires pros to manage it.
Frankly this is the beginning… a couple of senior management types helping their boss, Rockefeller, to be a better angel investor.