Fichte's "empty form of knowledge"

This paper deals with Fichte's Grundzuge, and in particular with his discussion of the "empty form of knowledge" he claims stands at the centre of the third - i.e., the present - age. Fichte speaks of a fundamental principle that forms the "common denominator" between the third and fourth main epochs. This fundamental principle - the "maxim of comprehensibility" (Maxime der Begreiflichkeit) - makes knowledge and comprehension the measure of all that "counts as being valid and as really existing". But the question arises: How can one and the same principle act as the "unifying concept" for two different "main epochs of human life"? Does this not go directly against Fichte's claim that two main epochs differ from each other in every respect, precisely because they produce two entirely different "unifying principles", and because everything in them must reflect the difference between their "unifying principles"? Fichte's answer to this question is as follows: a) the fundamental maxim in question allows for two diametrically opposed interpretations, so that each of them provides the principle or the "unifying concept" from which the third and fourth main epochs arise, and b) the third main epoch only gives rise to the empty form of science, as opposed to "truly real science": it stands for a careless and easy-going, shallow, conventional, trivializing and incorrect conception of the "fundamental maxim of comprehensibility" - so that it misses what is essential, does not do justice to the fundamental maxim, overlooks its implications, and indeed goes against its innermost meaning.