What is the correct way to pursue self-enquiry?

AS: Bhagavan has said: 'When thoughts arise stop them from developing by enquiring, "To whom is this thought coming?" as soon as the thought appears. What does it matter if many thoughts keep coming up? Enquire into their origin or find out who has the thoughts and sooner or later the flow of thoughts will stop.'

This is how self-enquiry should be practised.

When Bhagavan spoke like this he sometimes used the analogy of a besieged fort. If one systematically closes off all the entrances to such a fort and then picks off the occupants one by one as they try to come out, sooner or later the fort will be empty. Bhagavan said that we should apply these same tactics to the mind. How to go about doing this? Seal off the entrances and exits to the mind by not reacting to rising thoughts or sense impressions. Don't let new ideas, judgements, likes, dislikes, etc. enter the mind, and don't let rising thoughts flourish and escape your attention. When you have sealed off the mind in this way, challenge each emerging thought as it appears by asking, 'Where have you come from?' or 'Who is the person who is having this thought?' If you can do this continuously , with full attention, new thoughts will appear momentarily and then disappear. If you can maintain the siege for long enough, a time will come when no more thoughts arise; or if they do, they will only be fleeting, undistracting images on the periphery of consciousness. In that thought-free state you will begin to experience yourself as consciousness, not as mind or body.

However, if you relax your vigilance even for a few seconds and allow new thoughts to escape and develop unchallenged, the siege will be lifted and the mind will regain some or all of its former strength. 

In a real fort the occupants need a continuous supply of food and water to hold out during a siege. When the supplies run out, the occupants must surrender or die. In the fort of the mind the occupants, which are thoughts, need a thinker to pay attention to them and indulge in them. If the thinker withholds his attention from rising thoughts or challenges them before they have a chance to develop, the thoughts will all die of starvation. You challenge them by repeatedly asking yourself 'Who am I?' 'Who is the person who is having these thoughts?' If the challenge is to be effective you must make it before the rising thought has had a chance to develop to a stream of thoughts.

Mind is only a collection of thoughts and the thinker who thinks them. The thinker is the 'I'-thought, the primal thought which rises from the Self before all others, which identifies with all other thoughts and says, 'I am this body'. when you have eradicated all thoughts except for the thinker himself by ceaseless enquiry or by refusing to give them any attention, the 'I' - thought sinks into the Heart and surrenders, leaving behind it only an awareness of consciousness. This surrender will only take place when the 'I' - thought has ceased to identify with rising thoughts. While there are still stray thoughts which attract or evade your attention, the 'I' - thought will always be directing its attention outwards rather than inwards. The purpose of self-enquiry is to make they 'I' - thought move inwards, towards the Self. This will happen automatically as soon as you cease to be interested in any of your rising thoughts.