There is an old saying; people tend to gravitate towards those of similar likes, dislikes, thoughts, and perceptions. This saying holds particular weight and fact when dealing with candidates, and their chosen vocation. For example if you find a Microsoft MVP, I guarantee you they are connected in some ways to other MVPs. People who are good at what they do, will always connect with others who are also good.
For those of us in staffing, therein lies the, one of the best sources for candidates. If you find a candidate who is very good, but for whatever reason you cannot land them, ensure you make a great impression, ask them if they know any others who might be a fit and be interested. See if they know any groups or communities that might be a good place to connect with other good candidates. Ask them if there is any knew break through or ideas going around about their skill, ask them what they would look for in a new job, in hiring of a candidate. Don’t just treat them as a candidate but also as a knowledge base, a resource, an untapped gold mine of possible, information, connections and candidates.
Remember the best always connects with the best.