At several points on the spiritual path, we may experience that reality asks more of us than we can give.
And this recognition may be especially acute after a good deal of practice, after the bulk of the work seems done, and after our attention is a little more fine-tuned.
The demands of precepts may seem unreachable. I can get there mostly, but I am always a little off, and there is a whole string of instances where I am clearly off the mark and it seems impossible for it not to be so.