The earliest examples of artificial life involve sophisticated automata constructed using pneumatics, mechanics, and/or hydraulics. The first automata were conceived during the third and second centuries BC and these were demonstrated by the theorems of Hero of Alexandria, which included sophisticated mechanical and hydraulic solutions.[2] Many of his notable works were included in the book Pneumatics, which was also used for constructing machines until early modern times.[3] In 1490, Leonardo da Vinci also constructed an armored knight, which is considered the first humanoid robot in Western civilization.[4]