Answer:
The metaphor he uses in "...And looked down one as far as I could...", implies that no decision is the appropriate one because nobody can assure you the results once the decision is taken.
Change is constant in life. And with change comes uncertainty. Every decision we must make is a risky one. A person must show composure when he or she needs to decide among two or more options.
On the part of "Then took the other one, as just as fair...", we can see that one or the other, the option we take has its advantages or disadvantages. The element of uncertainty is always present. That is why we need to always be prepared and trust in ourselves.
Robert Frost was a four-time Pulitzer Prize winner in poetry.