"Absolute submission is a form of freedom"
What is meant by this? I will take it to the most metaphysical degree: The Enlightenment mind seeks knowledge, to conceive and understand all truth, and the rules by which reality operates. As such it is seeking a kind of apotheosis: it wants to become, or replace, God. It sees this absolute understanding of concrete reality as reachable, and the attainment as its duty and prerogative. By attempting to acheive objective knowledge of reality, the subject strives to transcend subjectivity. It attempts to place itself, its own understanding, its apprehension, 'outside' of the ontological structure of reality so that it has an absolute perspective which is no longer relative or conditional.
Yet, God is no more free than the human. In fact, less so. God cannot act. Bound by the lower truth of the organisms which make 'Him' up (as the human is bound by the lower truths of society, biology, physics which constitute an individual). In attempting to escape from particularity (the relative truths we as subjects inhabit) we approach the Absolute, which is not only non-material, but entirely determined by the particular. Thus, the 'ruler', the master, is more trammelled than the slave. Although the slave is materially in chains, his actions determined at every point, it is precisely this freedom from action which allows the internal evolution and self-realisation. Humans attempt to escape themselves and by doing this, escape selfhood. The quest for absolute truth is the walking into an inescapable trap, our minds ossified by truths so concrete we can no longer bend within them.
One may then call this a kind of sublimation. Freedom from choice allows that energy to be put into another use. Absolute freedom, by contrast, seems to negate itself the closer it is approached. A kind of purity, a liberation, can be found within the strictures of obedience, and even a new kind of integrity, within absolute acquiescence.