Design conundrum...

I'm trying to figure out the most elegant way to solve my database design problem and I thought I pick some at the brains on this list. The problem involves 2 tables, one of editors and one of categories, both have unique ID numbers. Each editor can have authority over an arbitrary number of categories, and conversely, each category can have an arbitrary number of editors. So what is the best way to represent this in the DB? (Which is PostgreSQL 7 BTW) Right now I am considering using an array in one of the tables but I have heard that walking the array to check values is both slow and somewhat cumbersome. Is there a good way to do this with a third table maybe? Please don't hesitate to point out my stupidity if the simplicity of the solution indicates it. :) Thanks, -Jesse