Rabbi Nachman teaches,
Within the bounds G-d has set for man’s intelligence it is a great mitzvah, a positive duty, to sharpen the mind and understand as clearly as possible whatever the human mind is capable of grasping. However, there are certain questions (such as the paradox of man’s free will and G-d’s foreknowledge) the answers to which are beyond the capacity of the human mind to understand. Only in time to come will the answers be revealed. On no account should one delve into these questions.
It is said of those who speculate on such questions, relying on their own intelligence: “None who go to her return” (Proverbs 2:19 ) . It is impossible to solve these questions through reason. We must have pure faith. Even when it comes to the questions which do have a solution , there are times when the paths of the mind become blocked and one is unsure how to answer the non-believer who casts doubts in one’s heart. The remedy then is to study the codes of Torah law. If one still finds oneself confused and unable to answer these questions, one should rely on faith alone. The main thing is to have faith.
Likutey Moharan I, 62
With permission taken over from: Daily Dose Of Rabbi Nachman