One of Epicurus' central concerns is to show how human agency exists within a world whose ultimate constituents are simply extended and indivisible bits of matter (atoms) whizzing around in empty space (the void). A common way of putting this concern is to say that Epicurus wishes to defend free will against the threat of determinism. After all, the Epicurean poet Lucretius asserts that libera voluntas - often translated as 'free will' - is incompatible with causal determinism, and Epicurus (famously or infamously) posits an indeterministic atomic motion, the 'swerve', in order to defend our freedom against this threat. However, framing the issue this way risks anachronistically oversimplifying and distorting the Epicurean position. First of all, Epicurus defends at least three different sorts of freedom: “(a) Effective agency, our ability to act as we wish to in order to get what we desire. / (b) Self-formation of character, our ability to modify our desires, hopefully in a way that allows us to attain happiness. / (c) Moral responsibility, our ability to be justifiably subject to praise and blame for what we do.”