Which sentence best expresses the meaning of the following aphorism?
"For all sad words of tongue and pen, the
saddest are these, 'It might have
been.'"- Whittier

A sentence that can show the meaning of the aphorism shown in the question above is: It is better to do something than to regret never having done it.

This is because the aphorism shown in the question above shows that when we stop doing something, for fear of the result, we will feel very sad because we will wonder what could have happened if we had done that something. Furthermore, the aphorism states that this feeling is the saddest of all.

It is important to emphasize what an aphorism is, as this word refers to a sentence that conveys a moral principle.

In this case, we can conclude that the phrase "It's better to do something than to regret never having done" manages to express the same meaning as the aphorism, since it shows that the regret of not having done something is more painful than the doubt about what it would be the result if that action had been taken.

You can find more information in the following related questions:

 (Shows other examples of aphorism as well as its meaning.)