Meno supposes that virtue depends upon the person; therefore, a slave will have a different sense of virtue than a slaveholder would, and virtue would also be different for men and women. Socrates counters this idea by suggesting that virtue is something more general and is shared by all humans, regardless of gender, class, etc. Socrates guides Meno to this paradox:
You argue that man cannot inquire either about that which he knows, or about that which he does not know; for if he knows, he has no need to inquire; and if not, he cannot; for he does not know the very subject about which he is to inquire.
Socrates then engages the slave boy and uses his ideas on anamnesis to show that virtue is something common to all people and something that anyone can discover (learn through inquiry - in this case, Socratic questioning). In other words, Socrates shows that we all have inborn knowledge and merely have to remember it. We can recollect this knowledge; therefore, we can inquire about what we don't know in order to eventually know it (remember it). Socrates prompts the slave boy with the right questions to get him to remember this inborn knowledge.
As a slave boy, he might be honored to be included in this discussion and maybe even pleasantly surprised to discover that he has inborn knowledge and/or the capability of understanding and learning new concepts just as much as any other person. Given this notion of equality, that we all have inborn knowledge and a common virtue, the boy might suppose that is status as a slave is unjust.
If I were the slave boy, having been a slave all my life, I would find this discussion as an awakening. Socrates is showing me how to learn (or remember) geometric concepts; something I was never given a chance to do. And unlike my owner, Meno, Socrates says that virtue is something common to all people. This means that I am capable of the same virtues, including justice, as anyone else. This is seriously making me question my status as a slave. If we are all born with this innate knowledge and a common virtue, that is if we are all equal in this fundamental way, why am I forced to a life of servitude?
If everyone is capable of learning/remembering a common virtue, namely justice, then it would be incorrect for me to strive to be a virtuous slave while another person strives to be a virtuous governor/slaveholder. If virtue is a common thread for all humans (known before birth - as Socrates demonstrated with geometry) then I should also be able to recollect the same kind of virtue that a slaveholder would. And a virtue like justice seems to conflict with the idea of slavery in the first place. I will plan to inquire about this with Socrates when Meno is not around. It seems to me that Socrates is implying something more here. I am capable of learning geometry; to be sure. But he seems to suggest that if we all have a common virtue, then we are all capable of being virtuous, of being just. This means that all slaveholders are capable of learning/remembering this idea of equality and therefore capable of setting slaves free. I might also ask Socrates to help Meno "remember" this.