Consider if you will, the human being. The pinnacle of creation, most complex and intricate, mankind is a product of the personal handiwork of Hashem, as told to us in Parshas Bereishis (בראשית ב':ז'). We are each a combination of the earthly and heavenly elements, a coalescence of the physical and the spiritual (עיין בפירוש רש"י שם בד"ה ויפח). Bearing this in mind, it is not surprising to discover that the products and behavior of such beings are of equal complexity.
With the arrival of Parshas VaYigash, we learn about the depth of human action. Towards the beginning of the Parsha, the Torah tells us of Yosef's revelation to his brothers (שם מ"ה:ג'). The drama has built up and Yosef cannot contain himself any longer. The Torah states ולא יכל יוסף להתאפק לכל" הנצבים עליו...," "and Yosef was no longer able to restrain himself before all those who stood by him..."; he thus deems it necessary to reveal himself to his brothers and asks all others in the room to leave (שם פסוק א'). Rashi (שם) explains that Yosef could not tolerate the Egyptians standing there and witnessing the embarrassment of his brothers when Yosef would reveal himself; Rashi (שם), thus explains the word "להתאפק" as "לסבול," "to tolerate." This interpretation stresses Yosef's concern for the honor and dignity of his brothers; he did not want to be מבייש them ברבים, to embarrass them in public.
The Ramban (שם), however, quotes the Targum Onkelos as explaining the word "להתאפק" to mean "לאתחסנא," to control one's own emotions. This interpretation stresses a personal concern of Yosef's. He himself was unable to control himself anymore and thus wanted privacy when revealing himself to his brothers. The Ramban himself, though, disagrees with this view and says that Yosef was motivated by the pleading of the many Egyptians who were stirred and moved by Yehudah's powerful pleas. The Ramban thus translates "להתאפק" to mean "להתחזק," "to strengthen" or "to overcome"; Yosef could not overcome the pleading and, consequently, gave in to them and revealed himself. According to this, however, the question may be raised as to why it was necessary for Yosef to send the Egyptian bystanders away. To answer this question, the Ramban (שם) adds that to reveal himself in front of these Egyptians would have been damaging to Yosef, his brothers, and his people, when the Egyptians would hear about the brothers' actions against Yosef. This interpretation of the Ramban stresses that Yosef chose this time to reveal himself as a result of outside influences, namely, the requests of the Egyptians who were motivated by the words of Yehudah.
Undoubtedly, all of the above approaches reflect a shade of the truth. People's actions, in this case, Yosef's, are rarely the products of one single, simple cause. Our actions and decisions are products of all our feelings, thoughts, and circumstances. Any one decision that we make can and should take into account internal and external influences, such as those mentioned above. We must always be concerned with the impact and consequences of our actions if we are to be considered truly responsible for them. Perhaps this also explains why Yosef did not lash out at his brothers upon his revelation to them. Yosef realized that in a global sense, if the brothers had not sold him, the stage for the realization of his prophecies would not have been set. The brothers thus actually participated in the actualization of his dream.
In the poem called "Yigdal," we describe Hashem as "מביט לסוף דבר בקדמתו," meaning that Hashem sees the conclusion of a matter at its very inception. With this idea in mind, Yosef reacts to his brothers in an understanding way as he sees that their actions have fit into the grand scheme of Hashem; a part of the circle of life.