Do you remember the game concentration (some now call it memory)? A deck of 52 playing card are placed face down on a table. You flip over two at a time in an effort to match pairs of like cards. When a match isn’t made the cards go back on the table face down in the same location. When a match is made you add the cards to your pile and accrue points. The game is won by the person who makes the most matches.
What is your knowledge at the beginning of the game? Zero, right? It’s just like entering a room or community of people that you don’t know. You speak with one person and learn a little about them. You speak to the next and then another...before you know it you meet someone with a perspective and background that would help someone you met a little earlier. You introduce the two and voila - you've made a match!
Instead of earning points for matching cards when you make matches in networking you accrue goodwill. Goodwill is the only legal tender in networking. The more meaningful matches that you make the more goodwill you build.