From The Negro's Complaint by William Cowper:
By our blood in Afric wasted,
Ere our necks received the chain;
By the miseries that we tasted,
Crossing in our barks the main;
By our sufferings, since ye brought us
To the man-degrading mart,
All sustain'd by patience, taught us
Only by a broken heart;
Deem our nation brutes no longer,
Till some reason ye shall find
Worthier of regard, and stronger
Than the colour of our kind.
Slaves of gold, whose sordid dealings
Tarnish all your boasted powers,
Prove that you have human feelings,
Ere you proudly question ours!
I don't understand the meaning of the bolded phrase. Who taught whom?
A broken heart taught the slaves? This sounds odd.
I can't come up with any explanation. I would vaguely understand "taught us only of a broken heart" (these sufferings taught us to have a broken heart). But this by leaves me baffled.