In the depth of the night not daring to let any one know
I secretly took a huge stone and dashed it against my arm.
For drawing the bow and waving the banner now wholly unfit;
I knew henceforward I should not be sent to fight in Yün-nan.
Bones broken and sinews wounded could not fail to hurt;
I was ready enough to bear pain, if only I got back home.
My arm—broken ever since; it was sixty years ago.
One limb, although destroyed,—whole body safe!
But even now on winter nights when the wind and rain blow
From evening on till day's dawn I cannot sleep for pain.
Not sleeping for pain
Is a small thing to bear,
Compared with the joy of being alive...

What It Means

This is a placeholder explanation generated by the low-overhead model. It interprets "In the depth of the night not daring to let any one know
I secretly took a huge stone and dashed it against my arm.
For drawing the bow and waving the banner now wholly unfit;
I knew henceforward I should not be sent to fight in Yün-nan.
Bones broken and sinews wounded could not fail to hurt;
I was ready enough to bear pain, if only I got back home.
My arm—broken ever since; it was sixty years ago.
One limb, although destroyed,—whole body safe!
But even now on winter nights when the wind and rain blow
From evening on till day's dawn I cannot sleep for pain.
Not sleeping for pain
Is a small thing to bear,
Compared with the joy of being alive..." in the context of ""The Old Man with the Broken Arm" (a satire on militarism)" to mean that wisdom is timeless.