Parshas Netzavim

הַנִּסְתָּרֹת--לַיהוָה, אֱלֹהֵינוּ; וְהַנִּגְלֹת לָנוּ וּלְבָנֵינוּ, עַד-עוֹלָם--לַעֲשׂוֹת, אֶת-כָּל-דִּבְרֵי הַתּוֹרָה הַזֹּאת

"The hidden is for Hashem, that which is revealed is for us and our children forever, to upkeep all the words of this Torah."

The Chassam Sofer has a few nice peshutim on this posak.

There are many miracles that happen in this world. Most of them are hidden miracels that the human mind can't fathom and the eye cannot see. These are the miracles of everyday life, the things we take for granted. You happened to meet the right person, saw that something you need is on sale etc. and most of all just that we are alive and healthy. These are the 'nistoras' the hidden which only Hashem sees. There is one miracle that is 'niglah'- open for all to see. The fact that Klal Yisroel, after two thousand years of a dark bitter golus, is still around and we are still learning Hashem's Torah. That we survived a churban, Spanish inquisition, forced conversions, pogroms, holocausts and much more and we are still standing tall and Torah and mitzvos are growing is the greatest miracle that us and our children should see - that nothing stands in the way of 'lasos es kol divrie ha'Torah hazos"

A second prashat.
Every mitzva has many reasons why we do them and what consequences they cause in heaven. That is 'nistoras' the hidden part of the Torah. That part we have no need to know- that's for Hashem. What we do have to learn and internalize is the practicalities of the mitzvos and what they mean to us. The 'niglah' of Torah is for us and our childern to learn.
Theres a story told about the students of the Baal Shem Tov. The Baal Shem told them that the world stands on the Shofer blowing of the Noda B'Yehuda. So the students traveled to Prague- were the Noda B'yehuda was Rav, for Rosh hashana, to hear his shofer blowing. The Noda b'Yehuda got up before the tekias and gave a speech. He opened a Gemora Rosh Hashana. The Gemora asks why to we blow shofer on Rosh Hashana? The Gemora quickly interjects 'Why do we blow? The Torah commanded us to blow' The Gemmora then goes on to clarify what the question was. The Noda B'Yehuda just read that passage of 'Why do we blow? The Torah said to blow' closed the Gemora and thus finished his speech and started the tekias. The students were agahst, they traveled all this way just to hear the Gemora? And they asked their rebbi was this realy what kept the world going? The Baal Shem Tov answered that all the reasons that we know about performing any mitzva are called 'tammai hamitzvos' - the reasons of mitzvos. 'Tammai' can also mean just a taste. The highest leval of doing mitzvos is doing them because Hashem told us to do it. He explained to them that those that cannot get the right feeling of the mitzvos by just listening to Hashem - they need extra flavour, a taste the hidden meaning of the Mitzvas.