What did the first person to milk a cow think he was doing?

Honestly, i was writing a paper on commodities we take for granted, and milk flashed before my eyes and i thought to myself, What the hell was going through that persons head when they decided to milk a cow?
Honestly, imagine one day your walking around and you suddenly felt quite thirsty, the last thing your going to do is go up to a cow and milk it.

Your thoughts please. (Am i crazy for having this thought?)