前事不忘，后事之师

前事不忘，後事之師
qiánshìbùwàng,hòushìzhīshī
don't forget past events, they can guide you in future (idiom); benefit from past experience

CEDICT

Entry Composition

1 前事 qiánshì
  1. past events
  2. antecedent
  3. what has happened
2 不忘 bùwàng to forget not
3 后事 hòushì
  1. future events
  2. and what happened next... (in fiction)
  3. funeral arrangements
4 之 zhī
  1. (possessive particle, literary equivalent of 的 de)
  2. him
  3. her
  4. it
5 师 shī
  1. teacher
  2. master
  3. expert
  4. model
  5. army division
  6. (old) troops
  7. to dispatch troops