Possible Clues:

• '-- Woman'
• Decartes' conclusion
• "__ Sam": Seussian declaration
• Answer to 'Are you or are you not?'
• ''__ the Walrus''
• 15-Down's Sam- --
• Descartes's 'sum'
• "-- a Rock"
• The Lord, as introduced to Moses
• Sam ___ (Dr. Seuss character)