فَقَالَ صَاحِبُهُ: أَتُنْكِرُ أَثَرَهُ وَأَنْتَ تَرَاهُ فِي الطِّبِّ وَالزِّرَاعَةِ؟
He asked: Do you deny its effect while you see it in medicine and agriculture?
The interrogative challenges the denial by pointing to effects the listener can observe. Its second clause supplies evidence, so the question is not empty indignation; it connects reproach with an argument.
Without the examples of medicine and agriculture, the challenge would lose force. Both the contextual premise and named evidence help establish the intended meaning of the question.