Becoming Incarnation is in Process of Steps
Shankara preached Advaita Philosophy not only to show Himself as God, but also to show the possibility of becoming human incarnation to every human being standing Himself as a practical example. His intention was not to show Himself as God only and make others suffer mentally as in the case of a sadist, but also to show the way for Advaita to everybody. The Advaita Philosophy is not selfish capitalism, but, is a social capitalism to show the path to every poor man to become the rich man. In the selfish capitalism, a rich man claims himself as the only rich man wishing all others to be poor people forever. Such policy brings revolution either in Pravritti or Nivritti because the human psychology blended with ego and jealousy is always the same. One day or other, the patience will burst out. Therefore, Advaita Philosophy applied to the alive Human Incarnation is only to encourage every human soul to become God. But, the highest tragedy in this concept is that we should not aspire to become human incarnation in case we want to become the human incarnation! Thus, the entire spiritual knowledge is based on the preaching of these three sacred Preachers simultaneously at every stage.
Even the human incarnation is again in the process of some steps only. The first step is Kalavatara, in which a ray of His power enters you. You will be initially tested about your ambition and ego. The next step is Amshavatara, in which a part of the power enters you. In the next step, Aveshaavatara results, in which God enters you fully but for sometime only. Next is Purnaavatara, in which God enters you, staying throughout your life, but exhibits 3/4th of His power only (12 kalaas). In the final step, God enters and stays in you throughout your life expressing all the power (16 kalaas) and this is Paripurna Tama Avatara. The testing is done till the final stage.
Kapila belong to the first type. Vyasa belongs to the second type. Parashurama is an example of third type. Fourth is Rama and fifth is Krishna. Only Lord Krishna declared that He is God. Similarly, Shankara declared. Even in the fourth stage, Rama was tested by sages. When the sages told that Rama is God, Rama humbly replied that He is only a human being as the son of Dasharatha (Aatmaanam Maanusham…). Thus, this is a very long journey, which requires lot of concentration in the effort and lot of patience (Nishtha and Saburi as said by Shri Shirdi Sai Baba).