It's about three different modes of emphasis in fantasy role-playing games.
The warrior meets strategic and tactical combat challenges directly. The thief solves problems efficiently, but not necessarily directly. The wizard follows clues to one of the "correct" solutions.
The warrior came first, when fantasy adventure gaming was still just fantasy combat. The dungeon crawl introduced the thief, even before an actual thief class existed. And since clues to what threats would be faced helped wizards select their spells, this became the seeds of clue-trail-based scenarios, eventually becoming the dominant mode of games like Call of Cthulhu.
Success in the three modes is defined as:
- Warrior: facing the enemy directly and winning. Degree of success is based on losses suffered versus enemies defeated.
- Thief: finding any solution, direct or indirect. Degree of success is based on resources expended versus objectives retrieved.
- Wizard: figuring out all the clues to get to an official solution. Degree of success is based on facts discovered versus facts available.