http://www.metta.lk/tipitaka/2Sutta-Pitaka/2Majjhima-Nikaya/Majjhima3/129-balapandita-e.htm
"Bhikkhus, a man would throw into the ocean a plough share with a single hole in it. Then with the eastern winds it would be carried west and with the western windscarried east. With the northern winds it would be carried south and with the southern winds carried north. Then there is a blind turtle in the depths of the ocean and it comes up to the surface after the lapse of a hundred years. Bhikkhus this turtle with one eye to see would he put his neck in the plough share and yoke it to the hole to see light?"
"Venerable sir, it would happen after the lapse of a very long time."
"Bhikkhus, it is more likely that the blind turtle would put his neck in the plough share and yoke the eye to the hole to see light rather than the fool once fallen to hell would gain humanity. What is the reason? Here, there is no righteous living, good conduct, merit or a pleasant mind. Here they eat each other, the weaker one is eaten up. Bhikkhus, even if the fool regains humanity after a very long time he is born in a low clan such as with the out castes, the hunters, with the bamboo weavers, chariot builders, rubbish collectors or in such other low family. Born into a poor family without eatables, drinks and clothing, gains them with difficulty. He too is not with pleasant appearance has a deformed body and is with many ailments, either blind, deformed, lame or paralysed, or does not gain eatables, drinks, clothes, conveyances, flowers, scents, ointments, beds, dwellings and illuminations. He misbehaves by body, speech and mind and after death goes to decrease and is born in hell."