Greek philosophers
Chrysippus of Soloi
Chrysippus of Soloi was a Greek Stoic philosopher who was born in 280 BC in Soloi (present-day Soloi, Turkey) and died in 207 BC in Athens.
His teacher was Cleanthes of Assos, whom he then replaced as head of the Stoic school. Chrysippus chose as his main task to organize the teachings of his predecessors and give them a definitive form. In doing so, he prepared the way for the success of Stoicism in Roman times.
Chrysippus was born into a wealthy family but lost his inheritance due to the unfair practices of the lawyers, so he went to Athens to study. Here he wrote 700 books, only fragments of which survive and were used by his followers in their own works.
The philosophy of Chrysippus of Soloi was based on the work of Zeno of Citium, but was also influenced by Archesilaus, Ariston of Chios and especially Cleanthes. He modified the view of propositional logic. Under Aristotle, only correct judgments (propositions) were taken into account, but Chrysippus began to combine propositions ("If it is true that there is light in the day, and we know that it is day, therefore there is also light."). It was his work that was drawn upon extensively in the development of the modern propositional calculus in the 20th century.
He added to mathematics the important doctrine that the unit is a number.
According to Chrysippus, human life is fulfilled if it is honest. However, this is not given to man from birth and he must cultivate this state. He emphasized on meekness, knowledge, fortitude and truthfulness.