Therefore shall ye keep all the commandments - Because God can execute such terrible judgments, and because he has given such proofs of his power and justice; and because, in similar provocations, he may be expected to act in a similar way; therefore keep his charge, that he may keep you unto everlasting life.

Therefore shall you keep all the commandments which I command you this day,.... For the reasons before suggested, as well as for what follow:

that ye may be strong; healthful in body, and courageous in mind, for sin tends to weaken both; whereas observance of the commands of God contributes to the health and strength of the body, and the rigour of the mind; both which were necessary to the present expedition they were going upon:

and go in and possess the land whither ye go to possess it; the land of Canaan, they were marching towards in order to possess it; and nothing would more inspire them with courage, and cause them to enter it manfully without fear of their enemies, than obedience to the commands of God; whose presence being promised them on that account, they might expect it, and so had nothing to fear from the inhabitants of the land.

And this knowledge was to impel them to keep the law, that they might be strong, i.e., spiritually strong (Deuteronomy 1:38), and not only go into the promised land, but also live long therein (cf. Deuteronomy 4:26; Deuteronomy 6:3). - In Deuteronomy 11:10-12 Moses adduces a fresh motive for his admonition to keep the law with fidelity, founded upon the peculiar nature of the land. Canaan was a land the fertility of which was not dependent, like that of Egypt, upon its being watered by the hand of man, but was kept up by the rain of heaven which was sent down by God the Lord, so that it depended entirely upon the Lord how long its inhabitants should live therein. Egypt is described by Moses as a land which Israel sowed with seed, and watered with its foot like a garden of herbs. In Egypt there is hardly any rain at all (cf. Herod. ii. 4, Diod. Sic. i. 41, and other evidence in Hengstenberg's Egypt and the Books of Moses, pp. 217ff.). The watering of the land, which produces its fertility, is dependent upon the annual overflowing of the Nile, and, as this only lasts for about 100 days, upon the way in which this is made available for the whole year, namely, by the construction of canals and ponds throughout the land, to which the water is conducted from the Nile by forcing machines, or by actually carrying it in vessels up to the fields and plantations.

(Note: Upon the ancient monuments we find not only the draw-well with the long rope, which is now called Shaduf, depicted in various ways (see Wilkinson, i. p. 35, ii. 4); but at Beni-Hassan there is a representation of two men carrying a water-vessel upon a pole on their shoulders, which they fill from a draw-well or pond, and then carry to the field (cf. Hengstenberg, Egypt and the Books of Moses, pp. 220-1).)

The expression, "with thy foot," probably refers to the large pumping wheels still in use there, which are worked by the feet, and over which a long endless rope passes with pails attached, for drawing up the water (cf. Niebuhr, Reise, i. 149), the identity of which with the ἕλιξ described by Philo as ὑδρηλὸν ὄργανον (de confus. ling. i. 410) cannot possibly be called in question; provided, that is to say, we do not confound this ἕλιξ with the Archimedean water-screw mentioned by Diod. Sic. i. 34, and described more minutely at v. 37, the construction of which was entirely different (see my Archaeology, ii. pp. 111-2). - The Egyptians, as genuine heathen, were so thoroughly conscious of this peculiar characteristic of their land, which made its fertility far more dependent upon the labour of human hands than upon the rain of heaven or divine providence, that Herodotus (ii. 13) represents them as saying, "The Greeks, with their dependence upon the gods, might be disappointed in their brightest hopes and suffer dreadfully from famine." The land of Canaan yielded no support to such godless self-exaltation, for it was "a land of mountains and valleys, and drank water of the rain of heaven" (ל before מטר, to denote the external cause; see Ewald, 217, d.); i.e., it received its watering, the main condition of all fertility, from the rain, by the way of the rain, and therefore through the providential care of God.

Therefore shall ye keep {c} all the commandments which I command you this day, that ye may be strong, and go in and possess the land, whither ye go to possess it;

(c) Because you have felt both his chastisement and his benefits.

11:8-17 Moses sets before them, for the future, life and death, the blessing and the curse, according as they did or did not keep God's commandment. Sin tends to shorten the days of all men, and to shorten the days of a people's prosperity. God will bless them with an abundance of all good things, if they would love him and serve him. Godliness has the promise of the life that now is; but the favour of God shall put gladness into the heart, more than the increase of corn, and wine, and oil. Revolt from God to idols would certainly be their ruin. Take heed that your hearts be not deceived. All who forsake God to set their affection upon any creature, will find themselves wretchedly deceived, to their own destruction; and this will make it worse, that it was for want of taking heed.