From Samuel Clemens to Mark Twain

Some men get depressed because they failed to reach their goal. Success and failure can be deceptive and paradoxical. Because we can't go through both doors at once, we don't know how things would have turned out had we succeeded.

Mark Twain is a failed Samuel Clemens. The original ambition of Samuel Clemens was to be a riverboat captain. That's what he trained for and had some rookie experience, but the Civil War destroyed that goal, so he had to settle for "second-best" by becoming a fiction writer under the pen name Mark Twain. Had he succeeded in achieving his dream, he might have have had a fulfilling career as a riverboat captain. Been happy with his choice in life. But he'd disappear from history without a trace. No one remembers Samuel Clemens–they remember Mark Twain. 

Because he failed, that forced him to tap into an unsuspected talent. Think of all the successful people who never develop their full potential because they succeeded at something beneath their ability. Conversely, think of all the "failures" who achieve distinction at something they didn't plan on doing, and fell back on as a last-ditch compromise. Samuel Clements' bad luck was Mark Twain's good luck.