Fretless bass

For a long time I can't imagine I would ever play a fretless string instrument in my life. I mean, playing in tune seems impossible for me. But then I picked up violin and realized the possibility is there for sure. Still, fretless bass has that mystique, especially in the hands of masters like Jaco. I have no idea who first played fretless until I read this. The author thinks bass players should consider getting a fretless as a 2nd bass. Well, if I were to get my 2nd bass, I'd probably go for a 5-stringer.