 Finally, it should be recalled that for Leibniz there are quite distinct levels of perception among created substances. Some of these will be taken up in more detail in the following section, but the basic point for now is that the three major levels, from the lowest to the highest, are bare perception (without special distinctness or memory), sensation (with heightened distinctness and memory), and thought (with distinctness, memory, and reflection). These are distinctive of the three levels of monads, respectively, the bare monads, souls, and spirits. Only the last of these may properly be said to have reason. Only the last of these is strictly a mind in the Leibnizian classification.