(What maid will not the tale remember?)
In the first stanza the poet introduces the story, "the tale" that inspired his leap for glory and the poem itself. The tale of Leander and Hero, the poet assumes every maid will remember. The fact that this statement is put into brackets as an additional comment to the story shows that the story was very well-known at the time the poet wrote it; the poet assumes that every reader will know the story and will therefore understand his poem.
Fair Venus! how I pity both!
Hero was a priestess of Venus and Leander talked her into succumbing to their desire by telling her that Venus, goddess of love and desire, wouldn't like an inexperienced priestess. The poet sympathizes with their love and their tragedy.
For me, degenerate modern wretch
The self-criticizing poet sees himself as too comfortable, enjoying too much leisure and comfort of the modern time he lives in. However, his kinsman Leander from the past, being at the same place where he is now, swimming with the dangers of night and cold in December just to be with the one he loved.
