1. Cf. for instance my review of Anneliese Maier's Die Vorläufer Galileos im XIV Jahr hundert (Rome, 1949) in Archives Internationales d'Histoire des Sciences, 1951, pp. 769 ff., and her answer, "Die naturphilosophische Bedeutung der scholastischen Impetustheorie" in Scholastik, 1955, pp. 321 ff.

2. Thus the replacement of the qualitative approach by the quantitative (cf. infra, pp. 3, 18 ff.) appears to Dr. Crombie to represent a difference in degree, and to myself, to be a difference in kind.

3. A. C. Crombie, Robert Grosseteste and the Origins of Experimental Science, 1100-1700 (Oxford, Clarendon Press, 1953); also, A. C. Crombie, Augustine to Galileo (London, Falcon Press, 1952).

4. This seems to me to be an overstatement. Indeed in the passage quoted by Dr. Crombie (p. 59, n. 2) Grosseteste says only that in natural science there is minor certitudo propter multa bilitatem rerum naturalium, pointing out that according to Aristotle science and demonstration maxime dicta occurs only in mathematics, whereas in other sciences, though there is also science and demonstration, they are, however, non maxime dicta. Grosseteste is perfectly right as Aristotle distinguishes quite sharply between things that are necessarily so, and things that are so only in most cases, or habitually. Still, it is far from this statement to the probability thesis.

5. He learned this from Alexander of Aphrodisias, or Avicenna (cf. p. 158, n. 3) or even from Seneca.

6. Dr. Crombie insists upon the practical tendency of the teaching of the School of Chartres, of Kilwardby, etc. Yet Plato deplored the practical attitude and inspiration of the geometers of his time. And Archimedes was of course not only the greatest mathemati cian, but also the greatest technologist of the Ancient World.

7. It was, indeed, the inability of the AncientWorld to solve the problem of transporta tion that was the basic cause of its ruin.

8. Optics made no progress between Dietrich of Freiburg and Maurolico, or practically (as Maurolico's writings remained unpublished till the XVI century) between Dietrich of Freiburg and Kepler. But Kepler's optics, as Vasco Ronchi has shown, is not based on medieval conceptions, but signifies the "catastrophy of medieval optics"; cf. Vasco Ronchi, Storia della luce, 2d ed. (Bologna, Zanichelli, 1952).

9. J. H. Randall, Jr., "The Development of Scientific Method in the School of Padua," ournal of the History of Ideas, 1940; cf. my "Galileo and Plato," ibid., 1944.

10. Cf. p. 69: "The cause of having horns is not having teeth in both jaws, and not having teeth in both jaws is the cause of having several stomachs."

11. Petrus Peregrinus—and after him Roger Bacon—insist upon the necessity of manual work for the experimenter. Such is indeed the case at a time when the "artisans" are not skilled enough to prepare the instruments needed by the scientist. Thus Galileo, Newton and Huygens had to grind their lenses or specula themselves, etc. Yet, this is only a temporary situation and under the influence of science and its requirements an industry of instrument-makers develops and takes over the "manual work": astronomers—with very few exceptions —did not themselves prepare their astrolabes.

12. As a matter of fact, Dr. Crombie, though stressing its revolutionary character, admits himself that Grosseteste's methodology is essentially Aristotelian.

13. Thus, quite recently, H. Lange, Geschichte der Grundlagen der Physik, Bd. I (Munich-Freiburg, 1952), p. 159; cf. Duhem, Etudes sur Leonard de Vinci, II, p. 193; cf. contra Anneliese Maier, op. cit., n. I.

14. This view is expressed by Proclus and Simplicius and rigidly adhered to by Averroës.

15. This strange misinterpretation of Copernicus, whom Dr. Crombie moreover opposes to Galileo, saying (p. 309), "He [Galileo] refused to accept Copernicus' own statement that this was simply a mathematical device, a statement in keeping with Western astronomical opinion since the thirteenth century; the heliostatic theory was a literally true account of nature," is the only really important error that mars Dr. Crombie's excellent book. As a matter of fact, Copernicus never thought about his theory as being only a mathematical device and never made any statement that could be interpreted in that sense. It was Osiander and not Copernicus himself who expressed this view in the preface that he affixed to the first edition of the De Revolutionibus orbium coelestium in 1543—as in fact Crombie himself points out in his Augustine to Galileo: The History of Science A.D. 400-1650 (London, 1953, 1956), p. 326.

16. Cf. my paper "An Experiment in Measurement in the XVIIth Century" in the Pro ceedings of the American Philosophical Society, 1952.