The last blank of the sentence may be the simplest to fill in first. The scholar is known for writing on issues that are either large-scale or what seems to be contrasted to this, namely "small-scale." The word "minute" is not the same as the time measurement (i.e. minutes vs. hours). "Minute," in this context, means small. Thus, he wrote on minute, detailed topics as well as large-scale investigations. For such work, he was likely known for his vast learning and erudition. This does not mean he was known for his education or even his brilliance. "Erudition" describes having attained an impressive degree of learning and scholarship. Finally, we can guess that he has written many articles. (This is hinted at by the fact that he wrote "on many issues.") It is quite reasonable to describe these articles as being "innumerable."

The options given for this question contain many tempting, but ultimately less correct, answers. A "novice" is someone who is new to a given field or position, as is a "greenhorn." A "charlatan" is someone who lies in claiming to have a given set of skills or knowledge. One could very easily convince oneself that these sets are correct; however, the best hint for the answer is the "superficial grasp." A "dilettante" is specifically a person who gathers together various forms of knowledge without any interest in going deeply into the details. We might call such a person a "dabbler." He or she would accumulate knowledge on a variety of topics. "Sundry" means of several kinds or, merely, various.

Well, this is a somewhat strange sentence! Still, it is very approachable, so long as you pay attention to each clue. Note for the first blank that the sentence basically says that the Physics has a continuing worth, even though some of its facts are out of date. Thus, the worth endures or can be said to have an enduring worth. Now, for the second option, we are looking for something that expresses the idea of "giving a general direction." Whenever we get our "orientation", we get this general idea of the lay of the land. The word "orient" is derived from the Latin for east. Hence, getting your orientation could be understood as "finding East." This helps you to know your overall situation (indeed, all of the directions—North, South, East, and West). Finally, the last sentence really should only refer to something in the sentence.  It doesn't presuppose any philosophical knowledge on your part. Thus, if motion and change are the topics treated in the Physics, then it is safe to say that "mutability" is the best option for the third blank. This word is clearly related to words like "mutation" and "mutable," both of which deal with changes and alterations.