Sebald is talking of himself when he speaks of Browne. That is, his description of Browne is a self-portrait. He is describing his own artistic aims and his own sentences. The "parlous loftiness" he uses to describe Browne's perilously strung out sentences is presented in a writing style that is itself parlously lofty. So, what is this notion of loftiness that Sebald draws our attention to? What does he mean by using this metaphor of flight? Sebald continues to describe how he reads Browne:

     [B]ecause of the immense weight of the impediments he is carrying [the weight of erudition as well as the verbiage of his extraordinarily long sentences], Browne’s writing can be held back by the force of gravitation, but when he does succeed in rising higher and higher through the circles of his spiraling prose, borne aloft like a glider on warm currents of air, even today the reader is overcome by a sense of levitation. (19)