From the Rashi’s commentary:
– understanding [men]: [men] who understand [and derive] one thing from another. This is what Arius asked Rabbi Yose: “What is the difference between wise men and understanding men?” [Rabbi Yose said] “A wise man is like a rich money changer: When people bring him dinars to examine, he examines them. When they do not bring [money] to him, he sits doing nothing. An understanding man, however, is like a merchant money changer: When they bring him money to examine, he examines it, and when they do not bring it to him, he goes out and brings his own [money-i.e., he does not wait for people to come to him-he goes to them] (Sifrei).