When the asura king Bali sieged swarga (heaven) from Indra, the Lord incarnated to get Indra’s “land” back on the request of Aditi, the mother of the gods. But it actually turned out to be a test of Bali’s devotion and allegiance to dharma. As a human dwarf brahmin carrying an umbrella, Vamana asked King Bali to offer him three steps of land. When Bali made a promise, Vamana increased the size of his body. He covered the entire globe in a single step and the heaven in the second step. Because Bali had no more land remaining that he owned and could donate, he asked Vamana to place his lotus foot over his head to complete the third step.
In this first human incarnation of Vishnu, Bali’s greatness as a righteous being, in spite of being born in an asura family, is highlighted. He accepted the curse of becoming poor from his own guru Shukracharya but did not refrain from his promise of donating land to Vamana even after being informed that Vamana is Vishnu himself under disguise. Out of his devotion, he donated everything he owned, including all the results of his good deeds and his soul. Vamana broke Bali’s pride of being rich and separated him from materialism. Pleased with his superior devotion, Vamana then graced Bali with the company of Prahlada, Bali’s grandfather and Vishnu’s favorite devotee, and a new residence in a different world (loka) that was to be personally guarded by the Lord.
The incarnation teaches us that for the possessor of learning and spiritual knowledge, the world starts getting smaller and ultimately shrinks to the size of a single step. Even the solar system appears to be only a few meters long to the ultimate jnani who transcends maya. Vedic astrology too links Vamana with knowledge by associating this incarnation with the planet Jupiter, which is the significator for knowledge.