A successful scientist is generally a good observer. He makes full use of the facts he observes. He doesn’t accept the ideas which are not based on obvious facts, and therefore refuses to accept authority as the only reason for truth. He always checks ideas carefully and makes experiments to prove them.
The rise of modern science may perhaps be considered to date as far back as the time of Roger Bacon, the wonderful philosopher of Oxford, who lived between the years 1214 and 1292. He was probably the first in the middle ages to suggest that we must learn science by observing and experimenting on the things around us, and he himself made many important discoveries.
Galileo, however, who lived more than 300 years later(1564-1642), was the greatest of several great men, who in Italy, France, Germany, or England, began by degrees to show how many important truths could be discovered by observation. Before Galileo, learned men believed that large bodies fell more rapidly towards the earth than small ones, because Aristotle said so. But Galileo, going to the top of the Leaning Tower of Pisa, let fall two unequal stones and proved Aristotle was wrong. It was Galileo’s spirit of going direct to Nature, and proving our opinions and theories by experiment, that has led to all the discoveries of modern science.