How do we acquire character, how do we come to possess good qualities? By living according to the precepts of the vedas and sastras and by following the good customs practised by our own forefathers as well as by performing the rites that have been passed down to us. Good conduct springs from a good mind. So the mind must be free from evil.
Everybody does not possess a good mind. Look at your child. It is all the time up to some mischief or other. It cuts paper with scissors or cuts down little plants and shrubs. It is naughty all the time. When the same child is sent to school it is brought under a discipline. It has fixed timings to go to school and return home, to read its lessons, etc. It is no longer found to be wayward.
In the same way if we have no opportunity of being involved in evils thoughts and activities, we will also come under a certain discipline. That is why the sastras lay down rules to keep us involved in good works. When we are conducting religious rites we must have no ego-feeling. The preceptors of the Vedic way have shown us the path to consecrate our karma to Isvara. The Lord has given us strength to perform them but also the intelligence and the means. Even a little ego-sense would be ruinous because it is capable of taking many disguises and of sizing us at an unwary moment.
Are we able to see ourselves in a soiled mirror? If we dust it and clean it well, we can see our reflection clearly. Even a clean mirror cannot produce a proper image if it keeps shaking. The mirror must both be clean and steady; only then will the reflection be true and clear. The mind, the consciousness, is like a mirror. The Supreme Being is the only Truth. When there are no evil thoughts in us, the mind-mirror will also be clean. If it is fixed on a single object it will remain steady-like a mirror that does not shake. Only than will the Paramathma be reflected in it.
Who created this world? Who gives us food, clothing and comforts? Who is an ocean of grace? If we wish to know it is we must keep our mind steady and free from impurities.
Suppose a copper pot has remained immersed in a well for ten years or so. How much rubbing will it have to take before it becomes clean? The more we rub it the cleaner and brighter it will be. If our mind has been made impure with evil actions over many years it can be made chaste only by the performance of many a good deed, many a good-work.
Is it enough to keep the copper vessel clean for today? What will happen to it tomorrow or the day after? It will become dirty again if it is not rubbed. Similarly, we must keep our mind ever pure by the daily performance of good works. In due course, atime will come when the citta, the consciousness, will vanish and Self alone will remain. Thereafter, there will be no need to cleansed. Until then we have to keep our mind pure through good actions and good conduct.
For a general background, please see here