While walking he stumbles upon this beautiful plant and he decides to take it back and grow it
After months passed the plant grew big but it had this particular scent that we are all familiar with
He decides to get rid of it and burns it
While burning it he inhales THC and discovers smoking pot.
Of course this is not the true story but its a figment of my imagination but what I'm really sure of is that whoever was the first person who tried it he got so stoned and tripped so bad he got scared to death.
This is just my theory that i can't prove but man the whole point of the theory is to say that i'm willing to give up half of my life to experience what this person experienced.