textbook

When Anne got home that night she stacked all her textbooks away in an old trunk in the attic, locked it, and threw the key into the blanket box.

My backpack was always heavy with textbooks, and assignments seemed to never end.

The structures she revealed now appear in textbooks as if they had always been known, which is perhaps the strangest fate a scientific achievement can have: to become so obvious that nobody remembers it was once thought impossible.