To a large degree we are defined by our prevailing moods.  They illustrate our personality. They signal our character.  And deeper down, our prevailing moods set boundaries around our states of mind and to a large degree govern our thoughts and actions. 

Our prevailing moods are illustrations of our predominant emotions. They are also illustrations of our abilities to self-monitor and self-regulate. They illustrate our emotional intelligence. 

It seems there is a very curious linkage between our prevailing moods and our ability to perform. While psychological studies may or may not confirm it, observations suggest that the extremes of prevailing moods can generate the highest levels of performance. For example, many deeply depressed people excel in their chosen fields of endeavour (Churchill and Van Gogh come to mind).  And we all know people with pleasing personalities who achieve upper-level success in their chosen lines of work [Gandhi & JFK come to mind].

On the other hand, often, we are fooled by apparently-positive personalities.  For example, Robin Williams regularly presented himself as a zany, happy person. Yet, his real personality must have been quite different from the character/persona he presented in many of his highly-successful entertainment roles. 

So, we can be fooled by external performances. Theatre entertainers, movie entertainers, and TV entertainers fool us all the time – that’s their job. Perhaps, many of our day-to-day associates do the same thing to us? Perhaps, it is wrong to think we can accurately judge personality and character by external appearances.  We know it is better to watch what they do than listen to what they say. [That old-admonition/wisdom has been credited to John Locke, Andrew Carnegie, and others...I expect it dates back much further than these fellows.] 

But, clearly, on its own watching what they do isn't a sufficient strategy. 

Regardless, even if watching what they do is not a completely reliable way of gauging personality and character, we must still do it. While we observe them we must maintain a level of trust in other people...giving them the benefit of the doubt...not all of the time, but at least most of the time.  With a trusting mindset, we must observe them – to confirm we have gauged them accurately. And, we must do more than just watch what they do. We must read 'between the lines' of what they do. And we must ask them the right questions, so we understand why they are doing what they're doing. This combination of approaches will allow us to get a far better handle on other people’s personalities and character.