"That Mars is habitable by beings of some sort or other is as certain as it is uncertain what these beings may be," wrote Percival Lowell in the early 20th century.
While the theories of this well-heeled amateur astronomer might seem fanciful when viewed from 2025, given what was known at the time, a large percentage of the public found Lowell's theories about an inhabited Mars not just credible, but likely. Lowell went so far as to theorize that the planet was straddled by canals, designed and executed by hyper-intelligent beings, that would carry water from the poles to the equator of the apparently arid planet.
