All you really need to know is that without Boole's modifications strange things would happen in the PHI 520 logic course. But, given that the modifications exist it would be inaccurate to ignore them completely. Just know that the modern understanding of universal statements is that they make no claim about the existence of any members of the S class, while Aristotle assumed they did. Aristotle assumed people would never talk about things that didn't exist. At very least, if this were possible, we would be forced to re-think our definition of validity and the relation between premises and conclusions, which would cause a great upheaval in the study of logic.
All electric motors are machines that depend on magnetism.
No tax audits are pleasant experiences for cheaters. Some people who attend Grateful Dead concerts are people who don't use drugs. Some people who listen to Henry Rawlins' CD's are not violent people. It's false that some birds are fish.