1. Rational
2 ratonal
3.irrational
Thoreau mostly uses imagery to illustrate time in the excerpt. The second sentence is saying that he is in the midst of time/living, and he can "detect how shallow it is," meaning that he is aware that life is short and that the end is inevitable. Thoreau also describes time as being fleeting, but ever-present.
I hope this helps!
<span>Golden View Classical Academy’s mission joins instruction in the principles of moral character and civic virtue with a rigorous academic program. Virtue requires both a trained mind and a generous heart, and as such unites our ability to think and reason with our passions, desires, and feelings.</span>