A famous quote from Al Pacino's movie, the Devil's Advocate, brings to one's mind the question: why vanity of all? And why it is "definitely" the favourite sin? No one would argue that humans are sinners, all of them, but there are many sins out there to commit, which would look at a first glance more grave and evil. Take as an example the sins of murder, rape, torture, theft, or just being mean to someone and the list would go on. So again, why Vanity?
To answer the question, let's look at the definition of Vanity, or Vainglory (Latin, vanagloria) in English. We would find: "Excessive pride in or admiration of one's own appearance or achievements", and "Any idea, theory or statement that is without foundation". Digging a bit into the semantics of the word would take us to the excessive believe in one's superiority over all others, whether it was by appearance, achievements or any other quality, without foundation.
So what if a person is vain, should he be considered a sinner for that? One might argue that a vain person is proud, or he might have indeed acquired certain qualities that deserve to be praised. Here I would argue that pride is one's belief in his or her qualities, that feeling that each of us has and should have, in different scales. It gives us confidence and satisfaction, and encourages us to become better people. Vanity however, extends pride and includes the worst forms of selfishness, making the vain person believe that he has rights above others, and again, without foundation as goes in the lexical definition of the word, because no foundation can be found to justify Vanity.
In fact it is the greatest sin because it presents the basis for all other kinds of sins. Murder means claiming someone's life by the murderer, who believes that he has the right for that provided to him by vanity. Rape is claiming someone's inviolability; theft is claiming someone's property; Torture is claiming someone's wellbeing; Rudeness is claiming someone's self-respect. Vanity in its greatest forms would even give the vain a feeling of superiority above god. Think of any sin, and you would conclude that Vanity is the basis, and that is why it is "definitely" the favourite.
All of us have Vanity more or less, but let us try to keep it less, and a bit more of a pride.
