It is in their purely physical aspect, as complex processes of corporeal change, that [physical processes] are means to the maintenance of life: but so long as we confine our attention to their corporeal aspect,—regarding them merely as complex movements of certain particles of organised matter—it seems impossible to attribute to these movements, considered in themselves, either goodness or badness. I cannot conceive it to be an ultimate end of rational action to secure that these complex movements should be of one kind rather than another, or that they should be continued for a longer rather than a shorter period. In short, if a certain quality of human Life is that which is ultimately desirable, it must belong to human Life regarded on its psychical side, or, briefly, Consciousness.

Henry Sidgwick, The Methods of Ethics, 7th ed., London, 1907, bk. 3, chap. 14, sect. 3