What are the three sutras? They are the Flower Adornment (Avatamsaka) Sutra, the Shurangama Sutra, and the Dharma Flower Sutra. These three sutras are the invaluable words of Shakyamuni Buddha, recounted by the Venerable Ananda, and later recorded on palm leaves and circulated throughout the world. They are the sutras that every Buddhist should study and recite.
At the City of Ten Thousand Buddhas, all the left-home people and laypeople must be able to recite these three sutras from memory. At the very least, you must be able to recite the Shurangama Sutra from memory. You may memorize two of the sutras, or all three sutras, which would be ideal. But you must understand the sutras' meaning, and not just "swallow the date whole," that is, recite without understanding. If you don't seek to gain a clear under-standing, it's useless. If you can intuitively comprehend the state of these three sutras, then you will not have been a Buddhist in vain.
At the age of thirty, the Buddha sat under the Bodhi Tree and attained Proper Enlightenment. For twenty-one days, he remained in samadhi and spoke The Great Means Expansive Buddha Flower Adornment Sutra for the Great Knights of the Dharma-body (Bodhisattvas). This sutra encompasses the three treasuries and twelve divisions of the canon, and explains the perfectly fused and unobstructed state of the myriad phenomena of the universe, which is the state of the "One True Dharma Realm."
When the Buddha was sixty-two, the Venerable Ananda, because he valued only erudition and neglected cultivation, was snared by Matangi's mantra from the ancient Brahma Heaven, and was on the verge of destroying the substance of his precepts. The Buddha first used the Shurangama Mantra to rescue the Venerable Ananda from the woman's artifice, and then spoke for him the Sutra of the Foremost Shurangama of the Great Buddha's Summit. This is the sutra which activates our wisdom and reveals the principles. If we can take these principles and enlarge upon them, expanding their scope and making inferences from them, our wisdom will certainly become as vast as the sea.
At the age of seventy-two, for the great Arhats and great Bodhisattvas in the Dharma Flower Assembly on Spiritual Mountain (Vulture Peak), the Buddha spoke the doctrine of the One Buddha Vehicle, which is the doctrine for becoming a Buddha. At that point, those of the small vehicle turned from the small and went towards the great, and the Buddha bestowed predictions of future Buddhahood upon them. That's why the Wonderful Dharma Lotus Flower Sutra is considered the sutra for becoming a Buddha.
If left-home people were to study the sutras the way students study in school, it would be easy for them to memorize the three treasuries and twelve divisions of the canon. But after leaving home, they think they've already done enough. They may recite the Buddha's name, investigate Chan meditation, study the teachings, uphold the precepts, or learn esoteric dharmas, so consequently they don't study the sutras. Since they overlook the importance of studying the sutras, each generation is worse than the one before, and people turn into good-for-nothings--lazy gluttons. This is an unfortunate situation in Buddhism. If we don't correct this wrong thinking immediately, I cannot imagine what future Buddhism will have.