The Preface by Avatamsaka Bodhisattva, Great Master Cheng Kuan is a profound introduction to the sutra. Here it is, with comments by Master Hsuan Hua:http://cttbusa.org/preface/faspreface_contents.asp
Missing from the online version are these remarks by Master Hua found in the printed book:
Avatamsaka (Flower Adornment) Sutra
The Flower Adornment Sutra is the Sutra of the Dharma Realm and the Sutra of Empty Space. To the exhaustion of the Dharma Realm and empty space there is no place where the Flower Adornment Sutra is not present. Wherever the Flower Adornment Sutra is found, the Buddha is to be found, and also the Dharma and the Sangha of Worthy Sages. That is why when the Buddha accomplished Proper Enlightenment, he wished to speak the Great Flower Adornment Sutra to teach and transform the Great Knights of the Dharma Body. Since this Sutra was a Sutra of inconceivable wonder, it was then concealed within the Dragons' Palace for the Dragon King to protect. Afterwards, Nagarjuna-- "Dragon Tree" Bodhisattva went to the Dragons' Palace, memorized it, and brought it back.
The Flower Adornment Sutra is like an auspicious cloud in empty space, which extends throughout the Three Thousand Great Thousand World-System, raining down the sweet dew of Dharma rain to moisten all living beings. The Flower Adornment Sutra is also like the sun, which everywhere illumines the Great Thousand World-Realm, bringing warmth to every single living being. The Flower Adornment Sutra is also like the great earth, which can produce and grow the myriad existing things. Therefore, it can be said that any period in which the Flower Adornment Sutra exists is a period in which the Proper Dharma long remains.
Consequently, in our daily investigation and lecturing of the Flower Adornment Sutra, it is essential to rely upon the Sutra's principles to cultivate and to use the Sutra as a cure for our own personal faults. Those who are greedy, after hearing the Flower Adornment Sutra, should rid themselves of greed. People who have hatred, upon hearing the Sutra, should give up their hatred; and those who are stupid should stop being stupid. The principles discussed in the Sutra are designed to correct our faults and bad habits. It is absolutely not the case that the Sutra was Dharma spoken for Bodhisattvas with no relation to us, or that it was Dharma spoken for Arhats with no relevance for us. Don't think, "All I as an ordinary person can do is listen to the Sutra. I could never aspire to the states of a Sage." To think that way is to throw yourself away, to separate yourself from the Sages.
From the beginning to the end of the Flower Adornment Sutra, every phrase of the Sutra is an unsurpassed Dharma jewel. If we are able actually to apply and cultivate according to the principles in the Sutra, then we are certain to become Buddhas. For that reason the Flower Adornment Sutra can be called the Mother of all Buddhas. The Flower Adornment Sutra is the Dharma Body of all Buddhas. The Buddha praised the Vajra Sutra saying:
In any place where the Sutra text is found, there is the Buddha.
Wherever the Flower Adornment Sutra is, there is the Buddha. The Buddha is right there. It is just that your karmic obstacles are too deep and heavy, so although you are face-to-face with him, you do not see the Buddha. As it is said,
Face-to-face, not recognizing Guanyin Bodhisattva.
Right now our thousand-handed, thousand-eyed image of Guanyin Bodhisattva constantly emits unobstructed light which reaches all living beings with affinities throughout the entire Three Thousand Great Thousand World Realm; yet we here daily bow to the Buddha, recite the Buddha's name, bow to Guanyin, and recite Guanyin's name, but do not see Guanyin Bodhisattva. We just follow along with the crowd, bowing when people bow, reciting when people recite, which is just to be turned by the states of others and not actually to take it up into our own persons and minds.
"How, then, should I be in my daily bowing and recollection of Guanyin Bodhisattva? Should I continue to have a huge temper? Should I still retain my old faults and not change them?" If you are that way, you could bow to the exhaustion of the boundaries of the future, but you would never see Guanyin Bodhisattva. If you can change from evil and go towards the good, and truly rid yourself of your faults and bad habits -- doing your best to reform and become a new person -- Guanyin Bodhisattva is certain to come to your aid. That is why some people cultivate a good many years without opening the least bit of wisdom, while others cultivate and, without being aware of it, open their wisdom and acquire unobstructed eloquence. We Shramanas should diligently cultivate precepts, samadhi, and wisdom, and put to rest greed, hatred, and stupidity. In every move we make we should return the light and look within. If you cultivate that way, you will make progress. If we listen to the Flower Adornment Sutra, lecture the Flower Adornment Sutra, and recite the Flower Adornment Sutra, but fail to practice according to the principles of the Flower Adornment Sutra, the Sutra remains the Sutra, you remain you, I remain myself and others remain themselves, and we cannot unite as one. If we ourselves can become one with the Sutra by acting according to its principles, that is actual union with the Sutra. If you are unable truly to practice in accord with the Sutra, but instead are deficient in kindness and compassion with a dearth of joy and giving, having ignorance and afflictions as your only companions, then you have failed to understand the Sutra and lack the ability to listen to the Sutra. Upon hearing one phrase of the Sutra we should ask ourselves, "How should I act? Should I run after my faults and bad habits, or should I rely upon the principles of the Sutra and cultivate?" If you can constantly ask yourself that question, you will certainly obtain great benefit. The reason you have not obtained great benefit is simply that you look upon the Sutra as the Sutra, having no connection with yourself. Actually, when the Buddha spoke the Flower Adornment Sutra, it was spoken for all living beings including you, me, and everyone else of the present. The Buddha is face-to-face with us, speaking it for us from his golden mouth. When we listen to the Sutra, it is the same as having the Buddha take us by the ear and speak the principles right to our face, telling us to use the Sutra's Dharma doors to cultivate.
None of the Dharma doors goes beyond the self-nature of each one of us. Our self-nature, too, exhausts empty space and the Dharma Realm. Therefore, if you can expand and enlarge the measure of your mind, you will unite with the Flower Adornment Sutra, being two and yet not two. If all people can make the states of the Flower Adornment Sutra their own states and receive the Flower Adornment Sutra's limitless principles and infinite wisdom as their own, how vast and great that will be. As it is said,
It is vast and subtle.
Let it go, it fills the whole universe.
Roll it up, it secretly hides away.
That is ineffably wonderful!