To remedy this, the practice of one subject (should be made).
In plain words: To fix these problems, practice focusing on one single thing. The teacher says each person should find by experience which method helps them most.
Making the mind take the form of one object for some time will destroy these obstacles. This is general advice. In the following aphorisms it will be expanded and particularised. As one practice cannot suit everyone, various methods will be advanced, and everyone by actual experience will find out that which helps him most.
Namaste.
A calm guide to life, the mind and the old teachings.