From Buddhist monk, Ajahn Chah:
''Doing as you have been doing will not bring an end to doubt and confusion'', the Buddha told him. ''At this time, let go of the past; whatever you may or may not have done, whether it was right or wrong, let go of that now.
''The future has not yet come. Do not speculate over it at all, wondering how things may turn out. Let go of all such disturbing ideas - it is merely thinking.
''Letting go of past and future, look at the present. Then you will know the Dhamma. You may know the words spoken by various teachers, but you still do not know your own mind. The present moment is empty; look only at arising and ceasing of sankhārā (formations). See that they are impermanent, unsatisfactory and empty of self. See that they really are thus. Then you will not be concerned with the past or the future. You will clearly understand that the past is gone and the future has not yet arrived.
Contemplating in the present, you will realize that the present is the result of the past. The results of past actions are seen in the present.
''The future has not yet come. Whatever does occur in the future will arise and pass away in the future; there is no point in worrying over it now, as it has not yet occurred. So contemplate in the present. The present is the cause of the future. If you want a good future, create good in the present, increasing your awareness of what you do in the present. The future is the result of that. The past is the cause and the future is the result of the present.
''Knowing the present, one knows the past and the future. Then one lets go of the past and the future, knowing they are gathered in the present moment.''
Understanding this, that wanderer made up his mind to practice as the Buddha advised, putting things down. Seeing ever more clearly, he realized many kinds of knowledge, seeing the natural order of things with his own wisdom. His doubts ended. He put down the past and the future and everything appeared in the present. This was eko dhammo, the one Dhamma. Then it was no longer necessary for him to carry his begging bowl up mountains and into forests in search of understanding. If he did go somewhere, he went in a natural way, not out of desire for something. If he stayed put, he was staying in a natural way, not out of desire.
Practicing in that way, he became free of doubt. There was nothing to add to his practice, nothing to remove. He dwelt in peace, without anxiety over past or future. This was the way the Buddha taught.
But it's not just a story about something that happened long ago. If we at this time practice correctly, we can also gain realization. We can know the past and the future because they are gathered at this one point, the present moment. If we look to the past we won't know. If we look to the future we won't know, because that is not where the truth is; it exists here, in the present.