Half full...or just full of it?

A story gleaned from an e-newsletter I get:

A family had twin boys whose only resemblance to each other was their looks. If one was too hot, the other thought it was too cold. If one said the TV was too loud, the other claimed the volume needed to be turned up. Opposite in every way, one was an eternal optimist, the other a doom-and-gloom pessimist.

Just to see what would happen, their parents had "Santa Claus" load the pessimist's room with toys and games. The optimist's room was loaded with horse manure.

Christmas morning found the pessimist sitting amid his new gifts, crying bitterly.

"Why are you crying?" the parents asked.

"Because my friends will be jealous, I'll have to read all these instructions before I can do anything with this stuff, I'll constantly need batteries, and my toys will eventually get broken."

Meanwhile, the optimist was dancing for joy in the pile of manure. "What are you so happy about?" the parents asked.

To which he replied, "There's got to be a pony in here somewhere!"