"Nor, at the time, had it failed to enter his monomaniac mind, that all the anguish of that then present suffering was but the direct issue of former woe; and he too plainly seemed to see, that as the most poisonous reptile of the marsh perpetuates his kind as inevitably as the sweetest songster of the grove; so, equally with every felicity, all miserable events do naturally beget their like. Yea, more than equally, thought Ahab; since both tie ancestry and posterity of Grief go further than the ancestry and posterity of Joy."
Musing: Ahab has cracked his stump. When he cracked his wooden leg, a shard of wood pierced his skin and caused pain. Ahab considers how pain (the loss of his leg) can beget more pain (the piercing of his skin by the replacement), just as joy often brings with it more joy. And it seems true that the memory of sorrow stays with us longer than the thoughts of joy. I love how Melville reminds us that just as sweet, chirping birds have sweet, chirping baby birds, poisonous snakes have offspring too. It's all equal in nature. But if you are bitten by a snake, my guess is that stays with you longer than the song of a bird.