Simple:
* The professor's lecture on quantum physics was incomprehensible to the students.
* Her explanation of the problem was incomprehensible, leaving me more confused than before.
Adding Detail:
* The ancient text, written in a long-dead language, was incomprehensible to modern scholars.
* The chaos of the battlefield was incomprehensible to the young soldier, who had never seen such violence.
Figurative:
* His grief was incomprehensible, an overwhelming torrent of emotion.
* The vastness of the universe is incomprehensible to the human mind.
With Emphasis:
* The decision to go to war was utterly incomprehensible to the public.
* Her behavior was so incomprehensible that it bordered on insanity.
Remember to choose the sentence that best fits the context and the meaning you wish to convey.