write, book

書 is composed of 聿 (pen) and a variant of 者 (this, person). 聿 depicts a hand holding a brush for writing, while 者 depicts a pile of firewood being used to start a fire for cooking, and from the pile of firewood it extends to the meaning of accumulation or gathering. Therefore, 書 is used to mean recording knowledge with a brush and gathering that knowledge into volumes or books.