One of my favorite books is Ray Grigg's The Tao of Zen. His thesis, which he argues persuasively, is that Zen is rooted in Chinese Taoism, while Zen Buddhism is, obviously, rooted in Indian Buddhism.
Here's a lengthy excerpt from the "Buddhism in China" chapter. While it's possible to quibble with some of Grigg's conclusions, his basic contrasting of Taoist/Chinese and Buddhist/Indian approaches to life seems accurate to me.
The indented italicized passages are quotations from other writers. I haven't included the footnotes that show where the quotation came from.
As Buddhism in China was adjusted to fit Chinese sensibilities, the distinction between it and the Taoist sects and religions began to blur. In the common mind a synthesis of Buddhism and Taoism began to take place.
Chinese versions of the Buddhist scriptures were adapted to Chinese ideas, and Buddhism and Taoism were often mingled together in popular belief.
This mingling did not take place among the more literary and scholarly Taoists. For them the integration of Buddhism into China helped to define and invigorate the Taoism of the Lao Tzu and the Chuang Tzu.
Their Taoism involved ostensibly, no belief; it was and continues to be an aesthetic philosophy rather than a religion.
Mahayana Buddhism is a religion that evolved from a philosophical base. Taoism and Buddhism can be reconciled philosophically but not religiously. Those following the original form of Taoism have been unable to relate to the Mahayana aspects of Buddhism.
Even in the popular mind some of these differences were not so easily resolved.
Buddhism was in many ways distinctly un-Chinese. The Indian belief that human beings live over and over again on earth was entirely unknown in China. The Chinese reverence for the family clashed with the Buddha's teaching that family ties were a hindrance to enlightenment, and the celibacy required of Buddhist monks.
Where Buddhism saw life as suffering, Chinese tradition regarded the order of nature as fundamentally good and the right life as one lived in harmony with nature. Far from wanting to escape from the body and individual personality, most Taoists wanted to prolong their individual existence indefinitely.
In other words, a basic difference separates the character of Indian Buddhism and the native Chinese traditions of Confucianism and Taoism.
Taoism is earthy. It is basically optimistic. It accepts in general terms that life is worth living and that nature, personified in the metaphor of the Great Mother, is essentially a balanced beneficence.
Buddhism's character is more sober, less optimistic. As Richard Cavendish notes:
Although it has often been observed that Buddhism is a cheerful and good-hearted religion, the Buddhist attitude to life is intensely pessimistic. Life on earth is evil, painful and transitory. It is full of suffering and nothing lasts, nothing stays the same.
One of the characteristics of Zen that argues for a Taoist rather than a Buddhist origin is its lightness, its playfulness, its appreciative acceptance of life. Buddhism is serious, leaden, weighted down by Gautama's traumatic realization that suffering lies beneath the veneer of life's comforts, and pleasures.
The story of his own evolution from innocent prince to enlightened being is a revealing process. The emphasis is on the endurance and perseverance that the quest for enlightenment demands.
He struggles through seven years of wilderness meditation and asceticism before reaching realization. The same long struggle is reenacted later in China by Bodhidharma who sits persistently for nine years facing a wall. The literal truth of these stories is less important than the underlying attitudes they reveal.
The Chinese embrace life as worth living, and they seek ways of living it wisely and well. This is evident in the popular Kuan-yin, a maternal incarnation of the Buddha, who bestows fertility, safety, and comfort to her supplicants.
This same positive attitude is seen in the round and jovial folk-Buddhas of modern China who sit big-bellied and contented, or stand wide-legged and laughing. These images of the Buddha, unlike the austere and emaciated ones from India, invite a full and happy life.
Even in religion the Chinese enjoy life too much to waste it on asceticism and metaphysical exercises.
They would gladly sacrifice a few years for immortality as a good investment of time. They would willingly do t'so-ch'an (Japanese: zazen, literally "sitting meditation") to effect social harmony or attain worldly gain and influence.
But they would not expend much energy on something as abstract and metaphysical as enlightenment. "Once you had enlightenment," they would ask, "what would you do with it?" The question is expressed with an appropriate mixture of playfulness and practicality in a Zen story:
A Zen roshi and a Hindu guru were walking together along a riverbank and decided to visit an adjacent island.
"Let's walk to the island," said the guru.
"Why not take the ferry?" suggested the roshi.
"Because," said the guru, "I've spent twenty years learning to walk on water."
"Why take twenty years learning to walk on water," asked the roshi, "when you can take a ferry for a penny?"
The same grounded practicality characterizes the Lao Tzu. As Victor H. Mair points out:
The Chinese classic emphasizes political skills and social harmony in preference to the theistic orientation of the Indian scripture.
The Mahayana religious component in Ch'an and Zen Buddhism emphasizes the zazen in emulation of the sitting Buddha of India. Very practical reasons exist for doing zazen but they have been overlayed with exhortations to persevere, to be like the Buddha, to sit until all sentient beings are saved.
In contrast, the Taoist element in Ch'an and Zen Buddhism is not interested in such theological objectives.
The purpose of protracted sitting is not to perpetuate itself but to release the practitioner into the spontaneity and freedom of merely being. The end of the searching and discipline is a full and balanced life lived gracefully and harmoniously in wonderful simplicity.
The sitter returns to the village to become fully engaged in the profoundly ordinary business of day-to-day existence.
The Lao Tzu dedicates about half its wisdom to the affirmation of such worldly affairs. Although its treatment lacks the playfulness of the Chuang Tzu, it is nonetheless a clear confirmation of this life in this earthy place, fully committed to the worth that is inherent in the whole social and natural world.
Any discipline in Taoism is used to reenter fully what is already present. This is also the case in Zen.
Buddhism's discipline does not complete the cycle of leaving, returning, and reaffirming. It spins outward to become removed, unearthly, and austere, reluctantly present in the world as if living were a kind of selfless sacrifice.