Kant is associated with the Copernican Revolution not because his thought owed any particular debt to Copernicus, but because he regarded his synthesis of the empirical (i.e. what we can observe and record) and the a priori (innate understandings) as a "Copernican Revolution" in philosophy. This synthesis was summed up by his dictum that "perception without concepts is blind." The implications of this idea for moral philosophy were complex. Essentially, he tried to show that a person existed both in a "intelligible world," governed by reason; and a sensible world (the natural world, governed only by incentives. A moral decision was thus affected by the knowledge of what one should do (reached by reason) and what self-interest and incentives demanded. But Kant's association with Copernicus stems more from his rather immodest (but not unjustified) claim for his own philosophical advance than any effect that Copernicus had on his thought.