Classical texts did not delay scientific progress in Northern and Western Europe during the Middle Ages. The delay in scientific progress within much of the European continent during much of the Middle Ages was rooted in a pan-religious culture and social atmosphere-(specifically referring to Roman Catholic Christian lands and countries).
The Early Middle Ages were also nicknamed, "The Dark Ages", due to a prolonged period of anti-intellectualism, rampant superstitions and hyper-religiosity. Even when the more intellectually curious Late Middle Ages or "Age of Scholasticism" emerged, the sciences were not at the forefront of Clerical scholarship. Sure, the works of Aristotle were widely translated and read by the Catholic Clergymen of Northern and Western Europe during the Late Middle Ages; however, they were perhaps less preoccupied with Aristotle's biological and other scientific works, though were more interested in his cosmological works, such as, "The Metaphysics" and "The Soul", as early explanations that affirmed the indispensable existence and Prime Causality of God.
The earliest stages of European scientific development date to the Northern Italian Renaissance with some of the inventive and innovative ideas of Leonardo De Vinci, followed by the landmark discoveries, writings and teachings in Physics, Mathematics and Astronomy by Galileo. And of course, one can fit Nicholas Copernicus into this period-(Copernicus was not Italian, though was affiliated with The University of Bologna, either as a student or teacher during the Renaissance period). Additionally, the earliest Medical schools were centered in Northern Italy during the Renaissance period.
So, one can see that Christian Northern and Western Europe had a late start(historically and chronologically speaking) in the sciences, medicine and engineering when compared with the the Medieval Islamic world, as well as Ancient Greece, Egypt, Babylon, India and China.