לכו לחמו בלחמי ושתו ביין מסכתי, "Come and eat my bread, drink the wine which I have mixed.⁠" (Proverbs 9,5.)

In this verse Solomon compared the Torah to bread and wine, seeing that bread and wine are the principal sources of food for the body. Similarly, Torah and wisdom are the principal sources of nourishment for the soul. The reason why Solomon commences with the expression לכו, and did not say בואו, "come,⁠" is to teach that a person has to follow wisdom, i.e. go out in search of it and after the people who teach it. We find this verb used in this connection also in Proverbs 13,20: הולך את חכמים יחכם, "he who walks with scholars will himself become wise.⁠" The expression is unusual as we would have expected the author to say: "he who sits with the scholars will become wise.⁠" The only reason that in both instances Solomon used the verb הולך to describe how one is to relate to the scholars in order to benefit from their wisdom is to teach that one has to actively go after the wisdom which comes out of the mouth of the Torah scholars. One needs to denigrate oneself vis-a-vis the scholars; as a result one will absorb wisdom.
It is also possible that the reason for the use of the word לכו by Solomon is a hint that even if one has to travel a long way from one's home in order to acquire this wisdom one should do so. The message is that it is worth while to travel to distant countries in order to hear and study "My bread,⁠" i.e. Torah. The same thought is echoed by Isaiah 55,3 who quotes the Lord as saying: "incline your ear and come to Me, hearken and you shall be revived.⁠" God (The prophet) did not say: בואו אלי, "come to Me,⁠" as man sometimes has to travel to distant places in order to study Torah.
The words לכו לחמו בלחמי, may be perceived as "go to one another those who are anxious to eat of My bread.⁠" it is a warning to remove jealousy and envy from one's heart and that the scholars should not project an image of superiority which would prevent them from going to colleagues of equal stature. Most certainly they should not be arrogant enough to refrain from going to scholars who are of still greater stature. Wisdom increases through the interchange of ideas among equals. Our sages in Makkot 10 used the verse in Jeremiah 50,36: חרב אל הבדים ונואלו (concerning people who avoid studying in large groups) to illustrate this thought by understanding these words to mean "a sword against the loners!⁠" The prophet condemns the people who want to study in solitary meditation only. Not only do these people not increase their knowledge by doing so, but they are even apt to become foolish, i.e. arrive at faulty conclusions. In the verse quoted from Jeremiah, we have the word נואלו and we have a similar word in Numbers 12,11 i.e. אשר נואלנו, where it means: "we have acted foolishly.⁠" The message is clear.
Concerning the words: "drink from My wine;⁠" the letter ב in the word בלחמי in the first half of the verse appears superfluous. Why then did Solomon write it? Similarly, the letter ב in the word ביין also appears unnecessary. Actually, the letter ב in both instances means the same as in Genesis 41,2 where Ibn Ezra understands the letter ב in ותרענה באחו as not part of the word אחו. I believe that whereas when one drinks wine it is only healthy in diluted form, and damaging if drunk in its full strength, so that the word בלחמי and ביין could be understood as warning not to eat or drink all of the bread and the wine, the word מסכתי, "what I (God) have mixed" is to teach that when it comes to Torah and the performance of its commandments, all of them are to be studied and performed in undiluted form.
This simile contains yet another lesson which is worth mentioning. If someone spends a lot of time engaged in the pursuit of his livelihood, i.e. the needs of his body, and travels abroad in order to secure himself such a sound economic existence, even though he should have concentrated the major part of his energies amassing Torah knowledge, i.e. food for his soul, he errs, seeing that when one spends all kinds of energy on the amassing of Torah knowledge a measure of success is guaranteed, whereas the energy spent on the amassing of material wealth does not always result in success. Solomon encourages the pursuit of food for the soul more so than the pursuit of physical food for the body. He makes this plain in Proverbs 2, 4-5: "if you seek it (Torah) as silver, and search for it as for treasures, then you will understand the fear of the Lord, and will find knowledge of God.⁠"
Every single commandment may be perceived of as "soul-food;⁠" it provides the kind of nourishment which the soul will imbibe in the future when it is exposed to the brilliance of God's Shechinah in עולם הבא, the world to come. If one is able to perform commandments and good deeds locally, his reward is most certainly substantial; imagine how much more will be his reward if he travels far and wide in order to fulfill some of the commandments of the Torah! The reason is that he also receives a reward for the distance traveled and the effort and fatigue involved. We find proof of this when the eagerness to fulfill a commandment is described by the Torah (Exodus 12,28) as "they went and they did.⁠" Similarly, the Torah describes Moses' leaving the camp of the Levites in order to go to the camp of the Israelites in these terms. He could have waited for the Israelites to come to him and take leave of him. In fact, although they had all been assembled around him to listen to the rebukes, and he could easily have said his good byes then, he waited till each one of them had returned to his tent, and only then

וילך משה וידבר את הדברים האלה אל כל ישראל. בן מאה ועשרים שנה אנכי היום, וגו', "Moses went and spoke these words to all of Israel. 'I am 120 years old this day.'" It is possible that the 120 years Moses lived corresponded to the 120 days he spent on Mount Sinai. During the first 40 days he received the first set of Tablets. During the second 40 days he pleaded for God to forgive the people the sin of the golden calf; he spent the next 40 days on the mountain in order to receive the second set of Tablets. This may be the reason why he used the term אנכי instead of אני.
Our sages in Sotah 13 feel that he meant to say that on that day he was precisely 120 years old, i.e. that he died on the same day of the same month as he had been born. This may also be the reason why he used the word היום at the beginning of the previous Parshah, so that all these speeches took place on the same day. The day in question was the seventh day of Adar at the end of the Israelites 40th year in the desert. We have further proof of this in 34,8 where the Torah reported that the people mourned Moses for 30 days during which they did not journey. The Torah states explicitly that the days of Moses' mourning came to an end. It is proper to read this verse in conjunction with Joshua 1,10: "Joshua commanded the law-enforcement officers of the people: 'prepare for yourselves provisions for in another three days you will cross the river Jordan.'" Anyone reading these two verses together will realize that Joshua would not command the people to prepare these provisions until the mourning period for Moses had passed. To make this plain, the Torah had to write the verse: "the days of crying for (the death of) Moses had concluded.⁠" The Book of Joshua 4,19 reports that the Jewish people completed crossing the river Jordan on the tenth of the first month, i.e. 3 days after the conclusion of the mourning period for Moses. By counting backwards you will arrive at the date of the 7th Adar as the date on which Moses had died. When the Torah in Exodus 2,3 reported that Moses' mother was unable to hide him any longer, the date referred to is the 6th of Sivan, the day on which the revelation at Mount Sinai took place 80 years later. On that day, the light which filled only his parents' home on the day he was born became so powerful that it shone for the whole Jewish nation. The light which had filled the house of Amram had already forecast the eventual greatness of the boy that had been born to Yocheved. The reason Yocheved had to hide Moses in a basket, well insulated, was that the light surrounding the baby had become so much stronger that it represented a danger to the family. The Torah speaks of Yocheved having hidden Moses for שלשה ירחים 'three lunar months,⁠" rather than שלשה חדשים, "three months,⁠" (Exodus 2,2) to indicate that these were lunar months. The months Adar, Nisan, and Iyar are 29,30, and 29 days long, respectively. This gives us a total of 88 days during which Moses was kept "hidden" at home, or it takes us back to the 7th day of Adar as Moses' birthday. From all this it becomes clear that Moses died on the same day of the same month on which he had been born. The word חדש implies a period which equals 1/12th of the year, something not subject to variation either by adding or subtracting from it. The same is not true of the period known as ירח, a period which may comprise either 29 or 30 days. The reason why the Torah used the term ירחים in the verse mentioned was to enable us to calculate the precise date on which Moses was born. This prompted our sages in Kiddushin 38 to state that God completes the life cycle of the righteous from day to day (to grant them whole years) something they base on Exodus 23,26: את מספר ימיך אמלא, "I will fill (round out) the number of your days (meaning "years").

לא אוכל עוד לצאת ולבא, "I am no longer able to go out (to war) and to come back.⁠" Moses refers to the times he had led the armies of the Jewish people against Sichon and Og, respectively.
Nachmanides claims that the reason that Moses made this statement was to console the people about his impending death. No doubt, his physical powers had continued undiminished, as the Torah testifies about him in Deut. 34,7. He simply wanted to enhance the people's regard for Joshua who would henceforth lead them in battle, and ensure that they would inherit the land. Our sages in Sotah 13. understand the words: "to go out and to come back" as referring to words of Torah. They claim that Moses felt that his ability to teach the Torah had waned, that the fountains of wisdom had dried up for him. This by it self was a miracle as it prevented him from relating to his impending death with worry and sadness. God also allowed this to happen so that Joshua could take over from him during his lifetime.