How often have you heard colleagues say "that's my secret", often after being asked the solution to a specific problem. They're not being asked about their skills as a manager but rather on subjects that involve their 'secret' information - the 'gems' they keep to themselves in a bid to ensure their job security.
Keeping such secrets is not only detrimental to the individual but also to the company as a whole. There are many people who hold "key" positions, not because of the vital information they divulge and pass on, but rather what they keep to themselves, that which could cause damage should they no longer be around, or even cause a company to fold should the information be crucial enough.
There was a school once that had the perfect managers' training tool. Each junior pupil was given a mentor two years his senior. This mentor would school the junior in matters he did not grasp through normal teaching. Through this he developed his methods of passing on information. The mentoring also came with a responsibility, should the junior get it wrong the blame was directed at the mentor and not the pupil he was schooling. With this vital managerial skill now understood before leaving school how much better equipped he would be for the "real world".
Modern bosses have lost this vital key to true promotion, how many times a person is promoted by time served or when gaps develop in the structures due to resignations, retirements, or death. Promotion should only be granted when the person has successfully schooled a suitable replacement in every aspect of the old position. The ultimate test being that the promotee go on leave for a period of sufficient length so as to ensure the replacement is up to speed. Only when this test is passed should the promotee then take up his new post. How much better they will be as managers as they have learned a vital key, leadership is about serving rather than being served.
Companies too survive better with more staff knowledgeable about the company and "tricks of the trade". Companies that have people who pass on information, and in so doing become less vulnerable, are the most successful of all. This comes from managers that are willing to teach their subordinates whenever they require training and from the team spirit that develops with the exchanging of ideas and information. Managers who are available and willing to be mentors are also more revered than those who bellow "give it to me, if you can't do it I'll just have to do it myself". Such blurts are usually backed by feelings of insecurity (why was the junior asked to do the job and not me?) and threats of the subordinates superseding them (if he knows my tricks I'll be out of a job!).
The shoe fits far better on the other foot, the one where the echelon say amongst themselves "...have you seen what he knows? How much information he is feeding to the others? We must ensure we keep him, at all costs!".
The secret of success? To not have secrets, and to be willing to teach others to follow in your footsteps.