No more + as

"If you ask me to tell you anything about the nature of what lies beyond the phaneron… my answer is “How should I know?”… I am not dismayed by ultimate mysteries… I can no more grasp what is behind such questions as my cat can understand what is behind the clatter I make while I type this paragraph" - Martin Gardner.

I understood what the author tries to say at the first attempt, but I can't fugure out what as stands here for. Shouldn't there be than instead, as we usually say "no more than"? Could you please explanate it to me, maybe there's something I missed.
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