[T]here is a form of ‘meditation’ on ethical, spiritual and intellectual subjects. All our studies, reading, discussions, conversation and deliberations on such subjects are included in this ‘meditation.’ To read this book, and to think deeply about the subjects discussed in it, is a form of meditation. …

So, according to this form of meditation, you may study, think, and deliberate on the Five Hindrances (Nivaraṇa), namely:

1. lustful desires (kāmacchanda),
2. ill-will, hatred or anger (vyāpāda),
3. torpor and languor (thīna-middha),
4. restlessness and worry (uddhacca-kukkucca),
5. sceptical doubts (vicikicchā).

These five are considered as hindrances to any kind of clear understanding, as a matter of fact, to any kind of progress. When one is overpowered by them and when one does not know how to get rid of them, then one cannot understand right and wrong, or good and bad.