THE EXPLICATION OF THIS NARRATION

The important point in this narration is that knowledge and science from the time of the holy Prophets till the time of the infallible Imams (Peace be upon them) uptill the reappearance of the holy Imam are two part and through out this time it has not and shall never be more than two parts.

Because according to the saying of Imam al-Sadiq (Peace be upon him):

1- The entire knowledge and science brought by the Prophets are only two alphabets.

2- Till the time of Imam al-Sadiq (Peace be upon him) people never know more than these two alphabets.

3- The time by which the honourable riser (Peace be upon him) shall rise, he will bring out another twenty five alphabets together with the other two which shall be spread between the people.

From here that knowledge and science during the time of Imam al-Sadiq (Peace be upon him) till the time of reappearance of the holy Imam is so very spread than the time of the Prophets, then we must desist from the outward meaning of this narration and we must believe that Imam (Peace be upon him) intended another thing entirely which the narrator may not explicitly understand, because it is possible that the holy Prophet (Peace be upon him and his family) and the pure Imams (Peace be upon them) might have expounded a lot of knowledge and science which has not been expounded by any of the previous Prophet; is it that what the Messenger of Allah (Peace be upon him and his family) and his (wasi)  representatives has brought is the same science and knowledge brought by the previous Prophet and the household of the holy Prophet (Peace be upon them) hasn't made any transformation in it or they have not increased anything in it?

If that is the case, what is the preference and betterment of Islam over other religion?

It is obvious that person cann't believe that the science and knowledge of the holy Prophet (Peace be upon him and his family) is same as that of the Prophets before him (Peace be upon them).

Base on this, we must say that we need to ponder and think more before we can get what is meant by Imam in this narration because we can deduced from the outward of the narration that there is a kind of stagnation; i.e. from the period of the Prophets to the time of the pure Imams (Peace be upon them) and from that time to the time of rising of Imam (May our souls be sacrifice for him) is of one kind and shall continue to be one kind but with the rise of the holy Imam of the time the stagnation shall be break.

Presently if what is meant by similarity during the time of the Prophets and the period of the pure Imams (Peace be upon them) till the rise of the honourable Imam of the time (May our souls be sacrifice for him) is similarity in science and knowledge, certainly this is an explicit mistake because a lot  of knowledge and sciences has been expounded by Imam al-Sadiq (Peace be upon him) (who has stated this narration) and other pure Imams  (Peace be upon them) but such knowledge and science has not been quoted from other Prophets (Peace be upon them).

Base on this we can't claim that what is meant as similarity is the similarity in terms of level of knowledge especially when you take a look at increase in knowledge, but we can claim that the general way of obtaining knowledge (like benefiting through the sense of seeing and hearing) shall still remain as one till the coming of the leader of the time.