he is ignorant not knowledgeable. even if he knew that it was a being and before that he knew that it was not a being and that it would be his knowledge would have changed and his state would have changed so change would have been necessary since there is no meaning to change except the difference in knowledge. for whoever did not know something and then knew it has changed and he did not have knowledge that it was a being and then attained the state of existence so he has changed.
فهو جاهل لا عالم، وإن كان عالما بأنه كائن وقبل ذلك كان عالما بأنه ليس بكائن وأنه سيكون فقد اختلف علمه واختلف حاله فلزم التغير إذ لا معنى للتغير إلا اختلاف العالم فإن من لم يعلم شيئا ثم علمه فقد تغير ولم يكن له علم بأنه كائن ثم حصل حالة الوجود فقد تغير.