Every thing possible to be believ'd

What sort of literary work is William Blake?s The Marriage of Heaven and Hell? The ?Proverbs of Hell? might be read as a disjointed collection of aphorisms. Or, it may seem to be a curiously framed poem. The first two lines are ?In seed time learn, in harvest time teach, in winter enjoy./Drive your cart and your plough over the bones of the dead.? Their messages are typically discordant, and do not seem to have any thematic link. However, they are connected inescapably by the agrarian imagery that they invoke. In similar ways throughout the ?Proverbs? Blake makes it difficult for the reader not to hear a voice of continuity. This voice seems to often be sewn together by a faith in the possibilities of imagination. As he writes further on, ?Everything possible to be believ?d is an image of the truth.? His idea of truth is of something unbounded by earthly constructions; truth should not be limited, and so imagination is the only proper avenue towards it. The next line relies on a radically different image pattern, but emphasizes the same theme. He writes, ?The eagle never lost so much time as when he submitted to learn of the crow.? This line expands on the theme of the last line. Is this a poetic couplet? Are these lines linked thematically in the way that the lines above were linked through poetic language? Blake refuses to answer these questions, and relishes the ambiguity, the boundlessness of his peculiar poetic/aphoristic hybrid.