Galileo Galilei, the 16th-century scientist whose work has been called the foundation of all modern science, apparently copied many of his ideas almost verbatim from another scholar, according to a researcher at the Catholic University.

The Rev. William Wallace, a Dominican priest who has studied Galileo's manuscripts for the past 15 years, writes that he has found that all three of Galileo's most important notebooks show "considerable evidence of copying, or at least of being based on other sources. . . . Practically all of this material . . . dervies from textbooks and lectures notes that were being used at the Collegio Romano," a Roman university Galileo visited.

"Today people would call it plagiarism," Wallace said. "But at the time, everybody did it -- people then felt that ideas, when they were shown to be right, were automatically the property of everyone. . . .

"People were flattered to have their class notes used by another instructor.

I'm not saying Galileo was not the 'father' of modern science, just that there was a grandfather, too. What I'm holding is that the Scientific Revolution emerged gradually from the Middle Ages."

Wallace's thesis is a departure from the traditional view that little science was done during the Dark Ages, and that science, like art and scholarship, were reborn in the Renaissance, particularly in 16th-century Italy.

Galileo's Univeristy of Padua was far too conservative for such progressive ideas as experimental science and a physics based on mathematics, but the famous Jesuit College Romano was more progresive.

Only four sets of lecture notes remain from the Collegio Romano of the late 16th century, but all are very similar to Galileo's notebooks.

Wallace has compared the Latin text of those notes to Galileo's notes and later books, and found strong similarities of the ideas, and in some cases sentences copied verbatim, and in other cases passages with the same idea were italicized in each manuscript.

Wallace said he believes that Galileo and the four students copied the lecture notes of one professor at the Collegio Romano, possibly the Jesuit Paul Valla. Galileo then wrote them into his own lecture notes when he began teaching at the University of Padua.

The work at the Collegio Romano, according to Wallace, laid out the foundation of a mathematical physics, and foresaw the possibility of doing experiments to test it, as well as what the obstacles were. Galileo (1564-1642) is famous in large part because he gave physics a base in mathematics and carried out experiments in such areas as the trajectories of moving objects and what they implied about physical law.

Wallace is to publish his ideas in a book of essays due out later this year.