The conventional chef's hat, or toque blanche, is what is most unique and recognizable of the outfit, and also the piece which frequently leads to the most debates. Culinary artists as far back as the 15th century are said to have put on hats.
In the course of that phase artisans of all sorts (including cooks) were commonly imprisoned, or even executed, due to their freethinking. To get over persecution, several chefs searched for refuge in the Orthodox Church and hide between the monks of the monasteries. Being there, they were dressed in the same clothes as the priests-including their particular tall hats and lengthy robes-with the differentiation of one deviating trait: the chef's outfits were gray compared to priest's which were black.