The Rashba’s commentaries clarify that the word “bracha” (בְּרָכָה) is connected to the verb “lehabrich” (לְהַבְרִיךְ), which means to propagate vine with a method known today as “layering”.
In this method some of the grape vines are allowed to lie on the ground and then are partially covered with soil. The end of the vine is exposed and allowed to grow. As the time passes, roots begin to form on the stem buried under the soil. Finally the newly rooted cane is separated from the mother plant and replanted as a new tree.
If לְהַבְרִיךְ means to “draw” a vine, then לְבָרֵךְ means to draw the Divine light into the world.
This interpretation underlies most of the explanations given to the mechanism of “blessing” in the teaching of chassidus. Chassidic thought explains that the concept of blessing relates to the idea of drawing down influence, allowing for the person’s spiritual potential to become manifest. By saying a bracha, a person “attracts”, draws down the Divine light into what’s being blessed.
There is another aspect of a bracha, brought to light in the “Sefer HaChinukh” (an encyclopaedia of the Torah commandments for young people). It says that “bracha” is a way to express our gratitude and praise to haShem.
Actually there’s no contradiction between these two interpretations. Moreover, they complement each other. Both the idea of drawing down the light and the idea of gratitude are embedded in this single word “bracha” (see “Igrot Kodesh”, 7:1868). However, in the chapter “Vayechi” it is the first aspect that comes to the fore.
– The chapter “Vayehi” is focused on the blessings of Jacob to his sons. The blessing – “braha” – is related here to the word “attraction”. Bracha is the way to draw down the inner essence of Yaakov to his sons – the twelve tribes, and through them – to all the descendants of Yaakov in all generations. [Each and every one of Bnei Israel reveals the essence of Yaakov].
Based on the Rebbe’s talk on Shabbat Parashat Vayechi, 5752.