2nd paragraph of the Shema – Ask the Rabbi
Q. The Shema begins by saying God is One. Then it tells us to love Him with all our heart, soul and might. Is there any logical link between the two sentences?
A. Definitely. First we are told that He is one (Deut. 6:4), which means that He can not be divided. Then we are told to serve Him with an undivided heart and mind (Deut. 6:5).
The two sentences are reciprocal. The first is a statement that says that God is indivisible: the second is a duty to ensure that our loyalty to Him is also indivisible.
The sages pointed out that the word used for “your heart” (Deut. 6:5) is l’vav’cha, which has the letter bet twice, instead of lib’cha, which has the same meaning but has only one bet.
The heart has two inclinations, the good and the evil inclination, but, as Rashi explains, they must unite to serve God. How does the evil inclination serve Him? Understood as the human passions, it serves God by being brought and kept under control.