Thou canst not prove that thou art body alone,
Thou canst not prove that thou art spirit alone,
Nor canst thou prove that thou art both in one:
Nor canst thou prove thou art immortal, no,
Nor yet that thou art mortal—nay, my son,
Thou canst not prove that I, who speak with thee,
Am not thyself in converse with thyself,
For nothing worthy proving can be proven,
Nor yet disproven: wherefore thou be wise,
Cleave ever to the sunnier side of doubt,