Everything is by Divine Providence. If a leaf is turned over by a breeze, it is only because this has been specifically ordained by G-d to serve a particular function within the purpose of creation.
This is what man is all about; this is the purpose of his creation and of the creation of all the worlds, sublime and lowly -- to make for G-d a dwelling in the physical world ... A little bit of light dispels a lot of darkness ...
From the teachings of Rabbi Schneur Zalman of Liadi
The mind grasps the concept and envelopes it... [and] is simultaneously enveloped by the concept and immersed within it... This is a wonderful union, like which there is none other, and which has no parallel anywhere in the material world, whereby complete oneness and unity, from every side and angle, could be attained
From the teachings of Rabbi Schneur Zalman of Liadi
Rabbi Schneur Zalman of Liadi's "Tanya" is the "bible of Chassidism" -- the fundamental work upon which dozens of books and thousands of maamarim (discourses) by seven generations of Chabad Rebbes are based. The "heart" of Tanya is its 32nd chapter which discusses the mitzvah of Ahavat Yisrael, love of a fellow Jew.