al-Salāmu ‘alaykum wa rahmatullāh,
Sibawahyi is the forefather of Arabic grammar, the Imam of the grammarians, the first person to systemize the rules of Arabic grammar and present them in a book form to be available to the masses for generations to follow. Although there is doubt whether the contents of his book al-Kitaab are his words or the words of his teacher, al-Khalil ibn Ahmad al-Farahidi, there is no doubt that Arabic grammar is indebted to Sibawayhi.
There is an interesting story behind how he came to be the grammar genius he was though. As a young boy living in Basrah, he used to learn Fiqh and Hadith from the scholars there. One day he went to his shaykh Hamad al-Basri to learn hadith, but when he recited a hadith to his teacher he made a grammatical mistake [he made the khabar of laysa marfoo' instead of mansoob] which changed the meaning. His teacher interrupted him and said, "You made a grammatical error, O Sibawayhi!"
Sibawayhi did not like to have made such an error, so he made a promise, "By Allaah, I will seek out a type of knowledge by which nobody will be able to point out any errors I make!" He then went to learn from grammarians such as al-Khalil ibn Ahmad and others, and thus began the journey of Sibawahyi through grammar, which took him to the heights that it did.
Mind over matter.