Seeing the elephant was often given as the reason for going to the goldfields of California.

1. to see or experience all that one can endure.
Earliest mention in print- 1835, becoming fairly standardized by 1848.
Longstreet, 1835, in "Georgia Scenes," That's sufficient, as Tom Haynes said when he saw the Elephant.
Kendall, 1842, "Santa Fe Expedition," There is a cant expression, "I've seen the elephant," in very common use in Texas. ...When a man has seen enough, when he gets sick and tired of any job he may have set himself about, he has "seen the elephant."
2. to gain from worldly experience or to learn a hard lesson from experience; lose one's innocence; (hence) to see remarkable sights.
1842- But, Squire, I'll say no more, I've seen the elephant.
1854- Lewis, "Mining Frontier," I am a man who wandered 'from away down east,' and came to sojourn in a strange land and "see the elephant."

I think I remember that this was in an earlier thread.