Honor your parents so that your children learn to honor you. There is a fine story mentioned in the Purânas about this. The divine parents S'iva and Pârvatî once laid down a test for their two sons Ganapathi (Ganesha) and Subramanya. They were to go round the whole world and return to them; he who does it quicker will win the prize. Subramanya started quick and fast, and was pacing through highlands and lowlands, but Ganapathi walked quickly round the parents and claimed the prize.
He said: 'The parents are all the world' and the statement was accepted as correct. Ganapathi was installed as the deity supervising the acquisition of knowledge and as the deity who shall save all aspirants from obstacles on their path. The moral of this story is that parents have to be cared for and obeyed. That is the real Pitri-yana (Path of ancestors, through which the soul ascends to the lunar world to enjoy the benefits of ritual works).