Or HaChaim on Deuteronomy 8:1/אור החיים על דברים ח׳:א׳

1 כל המצוה, "All the commandment which I command you this day, etc." Precisely which commandment is Moses talking about? Besides, had he not already spoken about the need to perform all the commandments in verse 12 of the last chapter? What reason was there to repeat the same thing again at this point? Moses was a clever psychologist, familiar with the workings of the human mind and psyche. He realised that there is a built-in tendency in us to become progressively more lax in our observance, especially if we have performed a number of commandments meticulously and have chosen to perform one or two commandments with special attention to all its details. Once one has done this one is apt to look upon oneself as a pretty good Jew and one tends to be less punctilious with the performance of other commandments. People who are preoccupied with Torah study have a tendency to pat themselves on the back and to disregard some of the commandments which they view as being of minor significance. Such neglect is bound to result in such people suffering various kinds of afflictions; they may experience that others do not show them the respect which they feel is their due, etc. Moses therefore admonishes each and everyone of us not to forget to perform the whole (range) of G'd's commandments. The only effective way Moses found to bring this point across to us was by describing all of the 613 commandments as one single Commandment, i.e. כל המצוה.

2He resorted to a way of illustrating his point which is incontrovertible, based on the Zohar volume one page 170. Acccording to the Zohar man has 248 bones and 365 sinews. G'd commanded us 365 negative commandments and 248 positive commandments, one each to correspond to each of these parts of our body. If one suffers a pain or hurt in one of his bones or sinews he should examine which one of the commandments he had neglected so that the pain in question might be due to such neglect. A man will not be satisfied if in response to his cries of pain caused by the afflicted bone he is told by his doctor that seeing that 247 of his bones do not hurt him he should not really be complaining but count his blessings. Similarly, we must relate to each one of the 613 commandments. We cannot pride ourselves merely on the commandments we do observe but must be keenly aware of the damaging effect on our spiritual health of any commandment which we fail to observe when we have the opportunity. All of these considerations are included in Moses' reference to the need for us to observe the whole commandment, both the negative part and the positive part. The reason for this is למען תחיון, "so that you will live and multiply and come and inherit the land." Inheritance of the land of Israel is conditional on מצוה observance, which in turn is the guarantee of our spiritual and physical wellbeing.

3You may query that in the parable we presented the example does not match the subject matter of the Torah, i.e. אין המשל דומה לנמשל. In the parable we described the hurt experienced by a single organ upsets the entire body's balance, something that is not the case when applied to מצוה-performance. This is why Moses had to describe the commandments in the singular. He wanted to make it easy for us to appreciate that when the 613 commandments are viewed as a single unit that the non-observance of even a single one of them can destroy the entire balance of the fabric and throw everything out of kilter.

4ורביתם, "and you will multiply." This means that any potential obstacles to all these blessings will be neutralised through meticulous מצוה-observance, ensuring your continued unimpeded growth in numbers.

5ובאתם, "and you will come." This is one of the greatest messages in the Torah. Who was comparable to Moses in מצוה-performance, closeness to G'd, etc.? And yet Moses was not one of those to whom the promise "you will come to the land" applied! Surely there can be no more potent warning to the people at large to be careful not to become guilty of anything which would preclude them from attaining their objective of an inheritance in the Holy Land! תשמרון לעשות, "you shall observe to carry out;" The word תשמרון suggests that a person must keep a lookout for an opportunity to observe certain commandments which he has not had an opportunity to perform.

6The entire verse may also be understood by reference to Moed Katan 28 where we learned that there are three major blessings in life which one does not secure through merit but which are governed by "mazzal." They are: children, life (health), and a good livelihood (compare what we wrote on page 1810). Moses illuminates this subject from a new angle. He promises that if you will make every effort to observe all the commandments viewing them as an integral whole, you are assured of the three blessings which normally are subject only to the influence of "mazzal." He begins by describing the commandments in the singular, i.e. כל המצוה, and promises למען תחיון, life, ורביתם, children, ובאתם וירשתם, and you will get your inheritance, i.e. an ample livelihood. If you needed proof that matters which are subject to "mazzal" can become subject to G'd's personal providence, look at the example of Abraham who said of himself that he would not have children as his "mazzal" did not indicate that he would have them. Due to his gigantic endeavour to do G'd's bidding he eventually had many children in spite of his negative "mazzal."