Philosophical Works of Lucius Annaeus Seneca, Vol. 1

...although they gave it as explained in a much broader sense than the Peripatetics. Cf. Seneca, Ep. LXXXIX, 15. Now, indeed, even if the founder of the Stoa and his immediate successors preferred to use the method of Heraclitus most of all in establishing and cultivating this part of philosophy rather than that of Aristotle—whose definition of motion did not displease Chrysippus—the later Stoics nevertheless did not hesitate to subsequently turn more toward that doctrine of Aristotle and translate it into their own use. But the monuments of their literature, which were excellent (if indeed one may measure their merits and virtues by their fragments), were snatched from us by the envy of time and an unlucky fate; and from all this study of the physics of antiquity, impartial fortune has preserved for us nothing except the physical commentaries of Aristotle, Lucretius, and these Natural Questions of Seneca, which arose and were composed from assiduous study and the manifold [works] of the Greeks. Seneca depends so heavily upon their doctrine that there is no noteworthy passage in these questions that has not flowed from them, [authors] always faithfully praised by him, yet now for the most part lost.

Whence the value of these [questions] of no small moment can be sufficiently understood, since, without it, we would either not know many things, or would not know them correctly. Another merit of theirs, not to be overlooked, is contained in the fact that physics itself drew not a few increments from these same questions. For they were and remained almost the sole source for many centuries from which those who undertook to philosophize and expound on the nature of things drew their own, took the opportunity to think about it, and communicated their thoughts to others both privately and in person, as well as publicly and through literary monuments, until the books of Aristotle were transmitted to Western Europe for public use. Yet these were no impediment to the fact that whosoever touched upon physics, even with their fingertips, would openly confess that they had used Seneca’s Natural Questions as a most clear source:

Nor did their authority begin to wane until the sixteenth century and thereafter, when, with experiments and observations called to aid and ancient precepts and opinions subjected to examination, and with excellent instruments (which we use even now in improved forms) having been discovered time and again, this discipline began to be reduced to another and much better form by the Galileos and Torricellis.