Just as the naturally pure crystal assumes shapes and colours of objects placed near it, so the yogi’s mind, with its totally weakened modifications, becomes clear and balanced and attains the state devoid of differentiation between knower, knowable and knowledge. This culmination of meditation is samadhi.
When the modifications of mind have become weakened, the mind becomes like a transparent crystal, and thus can easily take on the qualities of whatever object observed, whether that object be the observer, the means of observing, or an object observed, in a process of engrossment called samapattih.
If we develop one state of mind through constant meditation, all other thoughts and desires will gradually recede. If we do not nourish our habits and distractions, they will wither and die. If we become one with the person meditating, the subject being meditated upon and the process of meditation, the mind is completely absorbed. If you put a red flower near a crystal, the crystal itself appears red; if you practice meditation regularly, the mind will take on that form. We should aspire to having our minds clear like crystals, through the process of one-pointed meditation.