Chassidus is built on davka

A classic letter of the Previous Rebbe (my translation):

Chassidus is built on davka—davka so, no different:

1. G–d could have created a spiritual world, not such a physical one, but He created davka a physical world.

2. G–d could have given the Torah and the Mitzvos to angels, but He davka gave the Torah and the Mitzvos to people.

3. G–d could have elevated all Jews to the heavens and given them the Torah and Mitzvos there, but He davka gave the Torah and the Mitzvos on this physical world.

4. G–d could have made matters such that people would have no evil inclination, and especially a Jew, but He davka created people with an evil inclination. (I shall reveal a secret: the Gemara says: “He who is greater than his fellow has a greater evil inclination.” [Sukkah 52a])

5. G–d could have made everyone love Jews, but He davka made matters such that all the nations hate Jews. (The mountain upon which the Torah was given is called Sinai. The Gemara says that “sinah [hatred] descended upon the non-Jews” [Shabbos 89a]: Since the Jews have such a beautiful, pure, wise Torah, they are hated.)

6. G–d could have made matters such that all Jews be chassidim, but He davka made matters such that misnagdim were first, and only then did the best ones become chassidim.

7. G–d could have made matters such that all chassidim have good heads and good hearts, but He davka made matters such that chassidim have average heads and very average emotions.

8. G–d could have made matters such that all chassidim have chassidishe, religious children, but He davka made matters such that all chassidishe children’s minds are dreaming with confusion—they themselves don’t know what they want.

So we find that there are many davkas—davka so, no different.

It’s all about davka:

davka to create a physical world,

davka to give the Torah and the Mitzvos to angels, not people,

davka to give the Torah and the Mitzvos on the earth,

davka to create people with an evil inclination,

davka that the Jews be hated,

davka to be born misnagdim first,

davka to first have a simple head, etc.,

davka to that the children should first be in a state of tumult, and then set themselves on a healthy path.

All these davkas, and tens of thousands more, depend on one davka—that one should davka want the truth.

Then, even a chassidishe child,

even with a simple head,

born a misnagid,

and a Jew, whom everyone hates,

with an evil inclination,

on the earth,

not an angel,

in a physical world

will be able to refine his simple head,

and refine his simple, coarse emotions,

and then become from a misnagid, a chossid,

and all nations will acknowledge that a Jew should be loved,

and the evil inclination will become a good inclination,

and the physical world will begin to shine cleanly and purely, like the heavens,

and then the angels will recognize that [Jewish] souls are higher ...

Igros Kodesh of the Rayatz, Vol. 1, pp. 448-450.