The Talmud: Selections, by H. Polano, , at sacred-texts.com
Rabbi Meir said, "When a man teaches his son a trade, he should pray to the Possessor of the world, the Dispenser of wealth and poverty; for in every trade and pursuit of life both the rich and the poor are to be found. It is folly for one to say, 'This is a bad trade, it will not afford me a living;' because he will find many well to do in the same occupation. Neither should a successful man boast and say, 'This is a great trade, a glorious art, it has made me wealthy because many working in the same line as himself have found but poverty. Let all remember that everything is through the infinite mercy and wisdom of God."
Rabbi Simon, the son of Eleazer, said, "Hast thou ever noted the fowls of the air and beasts of the field how easily their maintenance is provided for them; and yet they were only created to serve me. Now should not I find a livelihood with even less trouble, for I was made to serve my fellow-creatures? But, alas! I sinned against my Creator, therefore am I punished with poverty and obliged to labour."
Rabbi Judah said, "Most mule-drivers are cruel. They beat their poor beasts unmercifully. Most camel-drivers are upright. They travel through deserts and dangerous places, and have time for meditation and thoughts of God. The majority of seamen are religious. Their daily peril makes them so. The best doctors are deserving of punishment.
[paragraph continues] In the pursuit of knowledge they experiment on their patients, and often with fatal results. The best of butchers deserve to be rated with the Amalekites, they are accustomed to blood and cruelty; as it is written of the Amalekites, 'How he met thee by the way and smote the hindmost of thee, and that were feeble behind thee, when thou vast faint and weary.'"