Not all revolutions are heralded by such rhetorical drumrolls as "When in the course of human events" and "A specter is haunting Europe." Thirty years ago, on April 25, 1953, a revolution was announced by this bland sentence in the British science journal, Nature:

"We wish to suggest a structure for the salt of deoxyribose nucleic acid (DNA)."

The world shaken by that deceptively downbeat announcement was the narrow one inhabited by a few scientists competing with the intensity of athletes in a race to discover the structure of the chemical that controls heredity in all living things. But history is the history of ideas, perceptions, values--in a word, mind. So the wider world has been, and will continue to be, changed by the aftershocks of the intellectual earthquake that had its epicenter at Cambridge University.

The authors of the letter, Francis Crick and James Watson, won the Nobel Prize. Several dozen others have subsequently won for related work. The benefits from DNA research already include new medicines and agricultural hybrids. Many more blessings will flow from it. The potential danger is to something ancient: mankind's estimation of itself.

Nineteenth century biology, and especially the theory of evolution, seemed to suggest that mankind is not the apex of Nature's pyramid, but rather is a bead on a string--an early bead on a long string. Twentieth century biology threatens to make problematic the concept around which liberal societies are organized. It is the concept of the "self," the "expression" of which is the supreme liberal value. What is this self?

A 19th-century poet insisted, "I am the master of my fate; I am the captain of my soul." But what does mastery mean if so much is foreordained by a genetic code?

Darwin, Marx and Freud suggested that various kinds of change --biological, personal, social--are autonomous processes. Now biology opens the prospect of willful intervention in the chemical engine of existence. Some may view this as a reassertion of human autonomy, and hence of human dignity. But is it achieved by conceiving of the self as something reduced to chemistry? By affirming a radical materialism?

In 1980 the Supreme Court ruled that a living microorganism--a work of human artifice, a genetic engineering product with industrial uses --was patentable matter. It was a technical ruling of statutory interpretation (of the patent law). But the court held this: the fact that the manufactured product was alive was irrelevant to its patentability because it was a "composition of matter," just like a shoe or a better mousetrap.

Prof. Leon Kass of the University of Chicago wondered: are, then, human beings just "compositions of matter"? By teaching that matter is the only reality, the court, said Kass, is teaching "the homogeneity of the given world" and "the absence of any special dignity in all of living nature, our own included."

Liberal societies assume that individuals are self-constituting creatures, manufacturing themselves by free choices, assembling purposes and values from a limitless cafeteria of possibilities. The great novel of the great modern nation is about a work of art: Jay Gatsby's creation of his "self."

But is our autonomy an illusion dispelled by the deciphering of controlling genetic codes? When science seems to paint a demoralizing portrait of man reduced to a mere composition of matter, and when science seems poised to extend its manipulative conquest of nature to human nature, modern societies may wonder about their faith in the necessarily beneficent outcome of science.

Kass notes that modern political thinkers have anticipated a coupling of progress in science and morality: science would liberate mankind from the chains of necessity, and hence from defects. Defects are caused by neediness, which makes laws, religions and other oppressions necessary. Science would banish neediness.

Political thinkers of an older tradition trusted to law and morals to make men better. Those thinkers, Kass says, were skeptical about the benefits of unfettered inquiry. They feared that modern science would undermine the beliefs and conventions that hold man's passions in check. They argued that science would produce material progress, then luxury, then the unbridling of all appetites and the degradation of morals and taste. The conquest of nature around man would enslave man to the turbulent nature within him.

Which thinkers were right? Time will tell whether technical proficiency can be matched by prudence, whether scientific virtuosity can be controlled by virtue. Because a certain hubris is a byproduct of the permanent revolution of modern science, it is well to remember that, as Kass says, our inventiveness is not our invention, and nature is commanded only as she is obeyed.