This is an early 14th-century compilation of reflections, observations, quips and anecdotes by Yoshida Kenkō, translated by Meredith McKinney.
A man who was studying archery took two arrows in his hand and stood before the target.
"'A beginner should not hold two arrows,' his teacher told him. 'You will be careless with the first, knowing you have a second. You must always be determined to hit the target with the single arrow you shoot, and have no thought beyond this.' With only two arrows, and standing before his master, would he really be inclined to be slapdash with one of them? Yet although he may not have been aware of his own carelessness, his teacher was. The same injunction surely applies in all matters.
A man engaged in Buddhist practice will tell himself at night that there is always the morning, or in the morning will anticipate the night, always intending to make more effort later. And if such are your days, how much less aware must you be of the passing moment's indolence. Why should it be so difficult to carry something out right now when you think of it, to seize the instant?" (p. 66)