There was once a famous sculptor. One day he was visited by some people who wanted to see his work. He took them to his studio and showed them a number of pieces of stone that had been partly chipped away. None of the stone blocks resembled anything tangible and were far from being beautiful. The visitors were a little disappointed, for they came expecting to see aesthetic pieces of sculpture. Then the sculptor said: “This is where I start work on my creations; now let us go to the next room.” His visitors went to the next room and were confronted with objects that were beginning to look more shapely. They were more impressed. Then the sculptor led them to another room and showed them exquisite works of art. The visitors were delighted and exclaimed that they had never seen such delicate pieces of sculpture. But the sculptor explained that he had not finished work on them; they had yet to be polished before they reached the stage of perfection.
The gradual transformation that the visitors saw in the sculptures is analagous to the transformation that takes place in an individual when he practises yoga. At first his character is gross and unrefined. Something is lacking. Then in time, his attitude towards life, himself and others changes. His sensitivity increases. He starts to radiate that which is already within him. Yoga unfolds the inner being of the individual, in the same way that the sculptor slowly exposes the shape of his works. The shape is already inherent within the stone – the sculptor only cuts away the extraneous material that hides it. In the same way, the inner potential of the individual always exists – yoga merely cuts away the dross to allow it to show itself.

Taken from: Yoga and Kriya By Swami Satyananda Saraswati