What does the phrase ''Discretion is the better part of valor'' mean?

One definition of the Word"Valor" is the Word, " bravery." "Discretion" is a Word meaning "choice." To examine the possible results of a valorous deed before acting in an act of bravery is a matter of discretion. The result of said examination is your choice, or, discretion. 1. The discretion to act in a situation requiring valor or not act at all. Think of examples of that. Perhaps to save an enemy from certain death. 2. Or, when there are choices to be made in a valorous act. Hypothesis; Your pet dog whom you cherish is drowning. Another human being, a stranger, is also drowning. You can only save one. Which will be your choice? That is at your discretion. 3. It follows that making the right choice (which may vary, of course, in the eyes of others) will determine whether or not discretion, in a given instance, is the better part of valor. In saving one or the other from drowning, in the above example, it is clear that both acts, saving the dog or the human, are valorous. The choice, being discretion, would determine the meaning of the phrase; that "Discretion is the better part of valor." That does not give an answer to which is right and which is wrong but it does descibe the meaning of the phrase.