“Understanding the physiological and neurological features of spiritual experiences should not be interpreted as an attempt to discredit their reality or explain them away. Rather, it demonstrates their physical existence as a fundamental, shared part of human nature. Spiritual experiences cannot be considered irrational, since we have seen that, given their physiological basis, experiencers' descriptions of them are perfectly rational... All human perceptions of material reality can ultimately be documented as chemical reactions in our neurobiology; all our sensations, thoughts, and memories are ultimately reducible to chemistry, yet we feel no need to deny the existence of the material world; it is not less real because our perceptions of it are biologically based... It is not rational to assume that the spiritual reality of core experiences is any less real than the more scientifically documentable material reality.”