Ali didnt know/understand that he was appointed by the Prophet s.a.w at Ghadeer khum as the successor, but the Shias do. May be the Shias are smarter than Ali :P Sahih Bukhari Vol. 8, Book 74, Hadith 282: Narrated by Ibn Abbas: `Ali bin Abi Talib came out of the house of the Prophet () during his fatal ailment. The people asked (`Ali), "O Abu Hasan! How is the health of Allah's Messenger () this morning?" `Ali said, "This morning he is better, with the grace of Allah." Al-`Abbas held `Ali by the hand and said, "Don't you see him (about to die)? By Allah, within three days you will be the slave of the stick (i.e., under the command of another ruler). By Allah, I think that Allah's Messenger () will die from his present ailment, for I know the signs of death on the faces of the offspring of `Abdul Muttalib. So let us go to Allah's Messenger () to ask him who will take over the Caliphate. If the authority is given to us, we will know it, and if it is given to somebody else we will request him to recommend us to him. " `Ali said, "By Allah! If we ask Allah's Messenger () for the rulership and he refuses, then the people will never give it to us. Besides, I will never ask Allah's Messenger for it." With regards to the hadith prophesying the coming of the 12 Caliphs from the Quraish, it is a PROOF that the 12 Imams of the shias are not what the Prophet meant in his Prophecy because only 2 of the 12 imams became Caliphs, and one of them Al Hassan r.a. gave the Caliphate to Muawiyah r.a. So I think that the Shias here are not reading history properly.