Virgil is an appropriate guide to Dante at the beginning of the Divine Comedy because he is a pagan, and also describes Hell (the Underworld) in the Aeneid. <em>Dante calls him his master, nevertheless Virgil is not able to guide Dante to heaven, because he is a pagan, and is not allowed entrance. So, virgil guides Dante throught the darkness of hell, but not beyond that.</em>
The advantage is the specialist will be able to give you more info on what is wrong and a primary care physician can only give you as much info as they know. Like if your arm was broken you would want to go to a specialist because they know about more and a physician if you have a common cold.