I have noticed that concentration can be brought about in a number of ways.
These below are a few of them:
1. Following closely and concentrating into the object: this is the normal procedure used by beginners in developing concentration. The important point here is that:
I. It has to be done with mindfulness.
II. In metta bhavana, it has to have metta. Then we shut out all other objects – e.g. forms and sounds, and keep the mind on the object and nothing else.
2. Recalling the states of mind present in deep concentration and developing it through will power. In the second case one just has to bring one’s mind to stillness and draw it into states which are progressively deeper, subtler and more tranquil. This second method works better when one has experienced such states before.
3. By means of the mastery through resolution. A resolution is a certain decisive condition of the mind. By feeding the mind with wishes or intentions that are carefully worded, one makes it follow a certain mapped-out path of development.
This case is used for going to the specified jhanic states. For one well-versed in this practice, the mind would respond accurately and quickly to the resolution made. It is like feeding the computer with questions and getting results.