When serving G-d, one must as a rule proceed in order through each of the four successive levels–sister, companion, dove and perfect one. From the onset of one's service, however, one can and should be sensitive to the full meaning of serving one's Creator, especially to how the consummate service of "my perfect one" helps to perfect the world as a whole. This level of service cannot really be attained when one is far from the Light of G-d, for how can one eliminate darkness and pain by diffusing Light into the world if oneself is not yet an open channel connected to the source of Light?
Nonetheless, one can begin to shine light from the moment one starts to receive it. This Light will not be clear and bright; it will be hazy, like light rays shining through a fog. For this reason, in previous generations one was usually taught to refrain from actively spreading Light until one had become completely purified. However, in our generation, the need for spreading Light is immediate and urgent because the darkness of the exile–reflected by the emptiness caused by loss of identity–is exceedingly great. For the first time in history, therefore, our generation feels Divine Providence demanding that every Jew participate (in a perhaps limited but active sense) in the work of "my perfect one" as soon as he begins to awaken and return to the true path of life: Torah and mitzvot.
Every beginning ba'al teshuvah ("returner" to G-d and to true Jewish identity) must be deeply concerned and sensitive to the souls of his fellow Jews. He will then naturally express his concern by giving of his time and effort, both physical and spiritual, to help them, and by trying to radiate the Light that G-d has given him through the Torah.
Since G-d loves his people Israel as a father loves his children, the greatest expression of our love for G-d is our love for Israel–"to love that which the beloved loves". Devoted activity on behalf of other Jews continuously enhances consciousness of this truth, in turn motivating oneself toward more dedicated efforts to perfect Israel and the world.
Of all the teachings of the Ba'al Shem Tov, the founder of Chassidut, this is the essence.