מודים אנחנו לךThe eighteenth berakha of the 'amida, Modim, is the longest one and the main blessing of the third section of the 'amida known as hoda-a (gratitude). The Hebrew word modim actually means: "We thank... (You God)".
After having focused in the previous blessings on what we need and want from God, now we turn our attention to all what we have been given by God. Gratitude, Jewish gratitude, consists in the acknowledgment that God is the ultimate source of what we are, of what we have, and of all good things that happen to us.
The psychological effect of this berakha cannot be underestimated. "Modim" educate us. It trains us to feel a sense of endless indebtedness toward God. As if for a moment, we abandon our selfish sense of entitlement and we reassess the blessings that we usually take for granted. By enumerating the multitude of "gifts" we constantly receive from HaShem, this berakha opens our eyes to appreciate. Appreciation is the prerequisite for gratitude.
It is important to notice that we begin by thanking haShem for being our God. In other words, we express our gratitude to God for having chosen us among the nations.
Then, we turn our attention to the fact that we still exist as a nation, despite having so many enemies who wish we were not here. We acknowledge that our physical survival depends on Him.
This is the beginning of Modim
"We thank You, that You are HaShem, our God,
and the God of our fathers. (You are our God) for ever.
You are the Protector (tsur=rock) of our lives.
You are our Shield and Savior.
This berakha is so important (second only to magen Abraham) that our rabbis instructed us to bow-down at the beginning (modim anahnu lakh) and at the end of this blessing (hatob shimkha...).