Before us is Mishnah 18 in chapter 4 of Pirkei Avos (in some versions it is counted as Mishnah 14), and the author of the statement is Rabbi Nehorai. It is worth beginning with his name: 'Nehorai' is not his original name but a title - one who spreads light (from this same root comes the expression 'sagi nahor'). The identity of Rabbi Nehorai is not clear, and three opinions have been offered:
Rabbi Meir - whose name likewise indicates one who spreads light, and which is also a title rather than an original name.
Rabbi Nechemiah.
Rabbi Elazar ben Arach.
We have no way of deciding the matter, but we will explain the Mishnah as though it were said by Rabbi Elazar ben Arach, since the events of his life not only make its words easy to understand, but turn it into something deeply moving and meaningful.
The wording of the Mishnah:
"Hevei goleh li'mkom Torah" - a person must exile himself to a place of Torah.
"V'al tomar she'hi tavo acharecha" - a person should not say that the Torah will come after him.
"She'chavereicha yekaymuha b'yadecha" - he should not say that his friends will fulfill it and preserve it on his behalf.
"V'el binascha al tishaein" - he should not rely on his own understanding.
The first point of the Mishnah is clear: a person must leave the place where he is and go to a place that has an active, thriving beis midrash and rabbis from whom he can learn Torah, and he should not say that the Torah will come to him.
The story of Rabbi Elazar ben Arach:
As we learned in the second chapter, Rabbi Elazar ben Arach was one of the five students of Rabban Yochanan ben Zakkai, and in Rabban Yochanan ben Zakkai's opinion he was even the greatest of the five - "a spring that flows ever stronger," the inexhaustible wellspring of Torah. After Rabban Yochanan ben Zakkai passed away, all the students learned in Yavneh, while Rabbi Elazar ben Arach chose to move elsewhere: a place in Eretz Yisrael called by Chazal Diyomeses (Emmaus), which is not Yavneh, and was apparently a kind of resort town.
He reasoned that since he was, as it were, the greatest of the generation, people would come to him. But no one came. He enjoyed himself in his place while waiting for the students to arrive, and they did not arrive. The Gemara describes a truly tragic end: toward the end of his life he forgot all his learning, to the point that he could not read a verse properly. He could not even manage to read the famous verse "HaChodesh hazeh lachem," and read it mistakenly - in a way that is both tragic and ironic, as described there.
If he is indeed the author of the statement, his words take on added force. As Rabbi Nachman expressed this very point: a person should not say that the Torah will come to him, even if he is the greatest of the generation. And how much more so an ordinary person, who hears that a yeshiva is going to move to his city next year - he should not stay and wait for it, for he will lose an entire year in waiting. He should not lose even a moment, but should go to the place where the Torah is.
"She'chavereicha yekaymuha b'yadecha" - two explanations:
A person should not say that his friends will learn and then come back and transmit the material to him, for what one hears directly from the rebbi cannot be compared to what one hears secondhand from another person. According to this explanation, the letter shin is read as though it were a vav: and do not say that your friends will tell it to you.
Another explanation, directed at someone who is already a complete talmid chacham: do not remain in your place of residence thinking that the Torah will come to you, but rather go to the beis midrash - because the way to stay sharp and to develop one's Torah learning is through friends. According to this explanation, the reason for going to a place of Torah is that "your friends will fulfill it in your hand": a person needs his friends to help him uphold and preserve his own Torah.
"Ve'el binascha al tishaen":
This phrase is a quotation from a verse in Mishlei: a person should not rely on his own wisdom and understanding. The idea is that if he stays home hoping that the Torah will come to him, or if he is a talmid chacham who learns entirely on his own, he will end up being left behind. He will have no one with whom to clarify matters and make sure his mistakes are corrected. A person thinks he can learn by himself, but he is making a serious mistake.
In summary: The Mishnah instructs a person to exile himself to a place of Torah, to learn with other people, with the group, with the great ones and with the rabbis - for this is the only way to grow successfully and reliably, both as a beginning talmid chacham and as a complete talmid chacham like Rabbi Elazar ben Arach.