  Both senses of the term occur in Spinoza’s analysis of human perfection. At IV Preface Spinoza invokes a concept of perfection based upon a model of human nature that we set before ourselves. And Spinoza describes perfection of the human mind in terms of its power of thinking, as we have already seen, at IIIp11 and its scholium: the mind’s power of thinking is its perfection; joy is an increase in that power or a passage to a greater perfection; and sadness is a decrease in that power or a passage to a lesser perfection.