 As we have seen in Section 1.3, in Kant’s time, imagination and mental imagery were not systematically kept apart and a charitable interpretation of Kant’s claim would be that what is a necessary ingredient of perception itself is not voluntary imagination (as we don’t voluntarily imagine each time we perceive), but rather mental imagery (see Strawson 1974 and Gregory 2017 for discussion of just how charitable such interpretation would be). So the charitable interpretation of the Kantian Thesis is that mental imagery is a necessary ingredient of perception itself.