In plain words
Many people think that Vināyaka worship began only a little while ago. This is a great mistake: Vināyaka worship is ancient, not new. Even in the Nārāyaṇa Upaniṣad there is a prayer to Vināyaka;
“We know that Supreme Person; we meditate on the One with the curved trunk; may the tusked One impel us.”
In the Ṛg, Yajur and Sāma Vedas there are mantras on the worship of Vināyaka. Of all the festival days, the festival of Vināyaka Caturthī is the very first to come. Only after it do the other festivals come. Whether for entering a new house, for beginning studies, or for building... before beginning any work at all, you must first pray to Vināyaka. He alone is the lord of Siddhi and Buddhi. That is why they regarded Siddhi and Buddhi as his wives. If you want Siddhi, there must be Buddhi. If there is to be Buddhi, you must have gratitude. In one who has no gratitude, Buddhi perishes. Once Buddhi has perished, it is impossible for Siddhi to come. “However much you cherish a small-minded man, in the end he does harm even to a great one.” You must not be such petty people; you must be great.
You must keep in mind all your life the help you have received from others, and show them the gratitude that is due. One who has no gratitude is no better than a cruel beast. One who shows no gratitude becomes like one who has put out his own eyes himself. When you do the sūrya namaskāras you say “Kṛtaghnaghnāya namaḥ”, don't you? What does it mean? Our eyes are able to see only because of Āditya. What is in our eyes is nothing but the reflection of Āditya. Āditya withdraws from the eyes of one who has no gratitude. That is, blindness befalls the ungrateful.
The body, the mind, the Ātma
Vināyaka is the one who brings strength of body, mind and spirit. In our college there is an MBA course. If you ask what MBA means, the children say Master of Business Administration.