The Talmud is a 2,000-page compendium that contains the wisdom and teachings of the Jewish sages. As a guide to Jewish law, it covers almost every area of life. Here are 21 quotes from the Talmud about human nature.

1. The liar’s punishment is that even when he speaks the truth, no one believes him (Sanhedrin 89b).

2. Once a person has sinned and repeated the sin, [he treats it] as if it has become permitted (Rav Huna, Arachin 30b).

3. The inclination only desires that which is forbidden (Jerusalem Talmud, Nedarim 9:1).

4. No two minds are alike, [just as] no two faces are alike (Berachot 58a).

5. Do not celebrate among the mourners, and do not weep among revelers (Kallah 10).

6. There is no community where everyone is rich; neither is there a community where everyone is poor (Jerusalem Talmud, Gitten 3:7).

7. A person’s true character is ascertained by three parameters: his cup (i.e., his behavior when he drinks), his pocket (i.e., his financial dealings), and his anger (Rabbi Ilai, Eruvin 65b).

8. Do not say something that should never be heard, because ultimately it will be heard (Hillel the Elder, Avot 4:2).

9. Anyone who introduces excessive fear into his house will ultimately cause three sins: infidelity, murder, and Sabbath desecration (Gittin 6b).

10. Be wary of authorities who befriend a person for their own purposes. They appear loving when it is beneficial to them, but do not stand by the other person in his time of distress (Rabban Gamliel, Avot 2:3).

11. Youth is a crown of roses; old age is a crown of thorns (Rav Dimi, Shabbat 152a).

12. When we were young [we saw ourselves] as men, now [we are considered] children (Bava Kama 92b).

13. The world is a dark place for one who looks to the table of others [for his sustenance] (Rav, Beitza 32b).

14. No one is [truly] poor, save for someone who is ill (Nedarim 4a).

15. If a person says I have worked hard but have not found [success], don’t believe him. [If a person says] I have not exerted myself, and I have found [success], don’t believe him. [If he says] I gave it my all and I have found [success], believe him! (Megillah 6b).

16. Do not appease a person while he is still angry (Avot 4:18).

17. A prisoner cannot free himself (Berachot 5b).

18. Just as you are obligated to speak when your words will be heeded, you must remain silent when you know your words will be ignored (Yevamot 65b).

19. If you have guarded your mouth from evil speech, your days will be peaceful (Derech Eretz Zuta 9).

20. Silence is beautiful for wise people; it is all the more beautiful for fools (Pesachim 99a).

21. Even a poor person who subsists on the charity of others should perform [acts of] charity (Gittin 7a).