Today, with Venus' acid clouds and scalding temperatures, life would never begin. But many years in the past, the clouds might not have existed and the temperatures might have been cooler, approximately at 15 degrees Celsius about 715 million years ago! In a speculative paper, by Mark Bullock, he suggested that if Venus had maintained its spin speed years and years ago, the planet might have been "toasty but habitable." Intriguing!