Read these lines from Robert Frost's "The Road Not Taken."

Oh, I kept the first for another day!

Yet knowing how way leads on to way,

I doubted if I should ever come back.

Which idea is conveyed by this part of the extended metaphor that is created throughout the poem?

Because a choice will take us in certain directions, it is not always possible to know what might have been.

If one choice does not work out the way it was intended, it is always possible to go back and change things.

Once a decision has been made, one should never look back and wonder what could have been different.

When torn between two decisions, it is best to remember that one can always go back and make a different choice.

The idea conveyed by those lines is Because a choice will take us in certain directions, it is not always possible to know what might have been.

Explanation:

The speaker of the poem "The Road Not Taken" has made a decision as to which path he is going to follow. In the lines we are analyzing here, he states he doubts he will ever have the chance to come back and try the other path. The reason for that is that he knows a way, once chosen, will lead to other ways and so on, until one has gotten too far to come back.

That metaphor, when applied to our choices in life, means we won't always have the chance to know what might have been. Once we make a decision, that decision will lead us somewhere and, from there, other decisions will be made.