Simplify the following text for a Grade 8 native English-speaking person.
Original: Historically mills were powered by hand ( mortar and pestle ) , working animal , wind ( windmill ) or water ( watermill ) .
Simplified: Small mills can be powered by hand , such as a mortar and pestle or a pepper grinder . Large grinding mills were usually powered by working animals , wind ( windmill ) or water ( watermill ) in the past .