Why is the "Hand of Hashem" all but imprerceptible?

Why does the Divine Providence present itself in this manner, blending miracles in the natural process, making the "Hand of Hashem" all but imperceptible? ... The answer to this question is to be found in the necessity to enable man to enjoy freedom of choice.  If man wishes he can discern the "Hand of God" in the innermost recesses of the most natural event and on the other hand he can disregard it int the most blatant of circumstances.

from the Sefer "Reb Chaim's Discourses"

The shmussen of the Mirrer Rosh Yeshiva Rabbi Chaim Shmulevitz ztl page 105

The end does not justify the means.

A person should not determine his course of action solely for the purpose of the accomplishment. A person is obligated to do that which is demanded of him, and it is for Hashem to bring results. It is incumbent upon man to act, not to accomplish.

Yosef's brothers justified their cruelty to him by their belief that he was a vainglorious dreamer. This was the cause of their ability to justify their actions. We have to be sure that every action we take is correct, regardless of the anticipated result.

from the Sefer "Reb Chaim's Discourses" The shmussen of the Mirrer Rosh Yeshiva Rabbi Chaim Shmulevitz ztl page 99

Woe to Us on the Day of Rebuke

The Midrash tells us that Yosef's brothers were overwhelmed by his rebuke, yet the Pasuk says that all that he said was, "Ani Yosef- I am Yosef".  Where is the rebuke that the Midrash refers to? 

This teaches us that rebuke is not verbal castigation that we have come to see it as, rather it is making a person aware of the the fact that he has erred.  When a person realizes that he has lived his life with a totally mistaken perspective, then rebuke has accomplished its purpose.

from the Sefer "Reb Chaim's Discourses" THe shmussen of the Mirrer Rosh Yeshiva Rabbi Chaim Shmulevitz ztl  page 98