Why did Buddha teach?

...

The question, O me! so sad, recurring -- What good amid these, O me, O life?

Answer.

That you are here -- that life exists, and identity;

That the powerful play goes on, and you will contribute a verse.

....

The above is an excerpt of Walt Whitman's poem, "O Me!  O Life!". It is probably the most popular poem nowadays, made famous by the movie Dead Poets Society and in turn, Apple's iPad commercial.

As a Buddhist, we know the Buddha's answer to life is the Dharma. But why did he spread the Dharma? Right after the enlightenment before the first sermon, Buddha Sakyamuni hesitated to teach. Supposing you are wearing his shoe, you are free of attachment. Was concerning sentient beings' sufferings an attachment? So, why did he teach?

In Why Did Brahmā Ask the Buddha to Teach?, Dhivan Thomas Jones mentioned the possibility that the hesitation was added later for the Buddhist to claim superiority over Hinduism since the Brahmā was subjected to the teachings of the Buddha. I doubt the assertion since it also means that the Buddha strove for fame. One can also say that the Buddha did that because it was a skillful mean for people to realize the Dharma's superiority. Recalling the story where the Buddha asked some would-be followers to respect their original teachers instead of him, I would say this was not his wish.

In Why the Buddha “Hesitated” To Teach, the author quoted that the Brahmā said there were those "with little dust in their eyes” for Dharma to teach. The Buddha surveyed the world with the "Buddha Eye" and concluded with 3 fields parable. For the sake of the rich fields (ready for harvest), for the love of the medium fields (waiting for cultivation by the wise farmer) and for the thought of the poor fields (cultivated only after the better ones have been cultivated) that the Buddha resolved “to set the Wheel of Truth in motion.” To declare the Dharma to all, the Buddha sees the world as "a single mission field."

He declared: "In this blind world, I will beat the Drum of Deathlessness!"

Unlike the previous Buddha Vipassī, he taught. The Brahmā asked and I think this is the reason.

In Ch'an (Zen) Koan, the question "Why did the Bodhidharma come from the west?" is a recurring topic. Even he arrived the east, he gazed the wall for 9 years before Huike asked for the Dharma. If Hukie hadn't asked, there would have been a different Ch'an. In other words, it is the ripening of Karma seeds (when someone asks for it) that constitutes the teaching.

So, I go back to Walt Whitman. His answer to life is to contribute a verse. Without "that life exists", one couldn't contribute a verse. Without the Buddha's life, without Brahmā asking for teaching, we wouldn't have the Dharma. The teachers didn't strive for teaching. When causes and conditions are ripen, they would “set the Wheel of Truth in motion.”

When causes and conditions are ripen, when you ask, Avalokiteśvara will help (see 妙法蓮華經觀世音菩薩普門品).

When causes and conditions are ripen, do you leave your dust there or do you ask for the broom?