You learn significant information about the target. This could range from the most up-to-date research, lore forgotten in old tales, or even previously unknown information. The spell gives you additional, more detailed information if you already have some knowledge of the target. The spell will not return any information for items not of legendary renown.
The knowledge you gain is always true, but may be obscured by metaphor, poetic language, or verse. If you use the spell for a cursed tome, for instance, you may gain knowledge of the dire words spoken by its creator as they brought it into the world.
Your intuition surrounding the target is enhanced and you gainon one Investigation check regarding it for each slot level above 6th.