Is a Cat a Substance?

If Aquinas is right about all this, then there's something misleading about a certain idea that most of us take for granted nowadays. Accidents make substances exist in certain ways, but they don't make them exist at the most basic level. In order to have an accident, the substance has to already exist. By acquiring wisdom, Socrates becomes wise; But in order to become wise, Socrates has to be there in the first place.