He has to study the man very closely and fine out what goal...
He has to study the man very closely and fine out what goal he set out on life's journey to attain, the opposition he encountered, the means he adopted to overcome it, and his ability to maintain the highest standard of character under the temptations and pressures of his long drawn out struggle with its many ups and downs. The historian will also have to judge whether the object, which the man set his sights on, was worthy of the sacrifices he made for it.
Then, and only then, will he be in a position to pass judgment on his life and say whether it was a success or failure. A close observation of conduct of Imam Ali throughout his life shows that his solitary object in life was to safeguard the interests of Islam, to defend it against the onslaughts of paganism, to see that its purity remained undefiled, and to ensure that it was running on the straight path that had been marked out for it by the Prophet (P).
Imam Ali was ready to give up not only the caliphate, but even his life for the Islam. The Victor of BADR and HUNAIN showed that for him, victory over his self was as easy as victory over formidable foes. Those who have had the experience of a struggle against the self know that it is much more difficult to gain victory over one's self than to gain victory over enemy armies.
The victors of AUSTERLITZ and DUNKIRK could not gain victory over themselves; Napoleon yielded to the temptation of marrying into a royal family of Europe to create a line of emperors, thus having to commit the misdeed of divorcing the loving Josephine, and was punished with waterloo. And Hitler's ambition to conquer the world (if we are to believe what we are told by his vanquishers) got the better of him and led to his downfall.
That Imam Ali did not secure the caliphate in the first instance is correct. He could however have done so without difficulty, had he left the body of his dead Prophet (P) alone and gone to the SAQIFA to present himself with the other candidates.
He would certainly have been chosen, because the only argument whereby ABU BAKR and UMAR managed to silence the ANSAR was that they were related to the Prophet (P) and were his heirs, while the ANSAR were total strangers, and that the Arabs would not agree to the rule of anyone who was not of the family of the Prophet (P). Imam Ali fulfilled these conditions to a much greater degree than ABU BAKR or UMAR, and in view of his services to Islam no one would have raised a single word against him.