Hidden light revealed to the righteous

במדרש סוד ה' ליראיו כו'.

In the Midrash: "The secret of Hashem is to those who fear Him [and His covenant, to make it known to them]" (Tehillim 25:14).

The Sefas Emes builds on the pasuk that Hashem reveals His "sod" (hidden secret) to those who possess yiras Shomayim.

דכל מעשיו של הקב"ה סתום וגליא וכן בכל מעשה בראשית אוצרות גנוזין כמ"ש אור הראשון היה מאיר מסוף העולם ועד סופו.

For all the works of HaKadosh Baruch Hu are concealed and revealed; and so within all of the work of creation there are hidden treasures, as it says that the primordial light (or harishon) shone from one end of the world to the other.

Everything Hashem made has both an outer, revealed face and an inner, concealed one. Within creation lie hidden treasures, like the original light of the first day that illuminated the entire world from end to end.

פי' שמאיר בכל מקום כענין שנאמר גם חשך לא יחשוך ממך

The meaning is that it shines in every place, in the manner of what is said, "even the darkness does not darken before You" (Tehillim 139:12).

This hidden light penetrates everywhere — even darkness is no barrier to it, for before Hashem darkness is as light.

והגם שהעולם הטבעי מסתיר הפנימיות היה כח באור הראשון להאיר תוך זה ההסתר רק שגנזו לצדיקים.

And although the natural world conceals the inner dimension (penimiyus), the primordial light had the power to shine within this concealment — only that He stored it away for the tzaddikim.

Although the natural order screens off the inner core of reality, the or harishon could pierce even that concealment. Hashem therefore hid it away, reserving it for the tzaddikim who are fit to access it.

והקב"ה מגלה הסוד והפנימיות להצדיקים וכ"כ בזוה"ק אמור בענין המועדות שיש בהם גילוי אור הגנוז כמ"ש אור זרוע לצדיק

And HaKadosh Baruch Hu reveals the secret and the inner dimension to the tzaddikim; and so it is written in the Zohar HaKadosh [on parshas] Emor, concerning the festivals, that they contain a revelation of the hidden light, as it says, "Light is sown for the tzaddik" (Tehillim 97:11).

Hashem discloses this concealed penimiyus to the righteous. The Zohar teaches that the moadim are special windows through which the hidden light shines forth — "light is sown for the tzaddik," waiting to be revealed.

וגילה הקב"ה לבנ"י סוד הזמן שהוא נגלה באלה המועדים.

And HaKadosh Baruch Hu revealed to Bnei Yisrael the secret of time, which is revealed in these festivals.

In the dimension of time, the hidden light breaks through specifically on the festivals — this is the "secret of time" that Hashem disclosed to Yisrael.

וכן סוד הנפש שהוא נגלה באבר המילה

And likewise the secret of the soul (nefesh), which is revealed in the organ of the milah.

In the dimension of the human person, the hidden light shines through the bris milah — that is the "secret of the soul."

וכן בעולם הסוד נגלה בארץ ישראל ובביהמ"ק.

And likewise in the [dimension of] world (olam), the secret is revealed in Eretz Yisrael and in the Bais HaMikdash.

In the dimension of space, the hidden light is revealed in the holy land and especially in the Bais HaMikdash — the "secret of place."

וע"ז כ' מה רב טובך אשר צפנת ליריאיך:

And concerning this it is written, "How great is Your goodness that You have hidden away for those who fear You" (Tehillim 31:20).

All this concealed goodness — the hidden light stored in time, soul, and space — is the "great goodness" Hashem reserves for those who fear Him, the yirei Hashem who merit to perceive His secret.

Summary: All of Hashem's works are "concealed and revealed," containing hidden treasures — like the primordial light that shone across all of creation and could pierce even darkness, which Hashem stored away for the tzaddikim. He reveals this hidden penimiyus to the righteous and to those who fear Him, across the three dimensions: the "secret of time" shines in the festivals, the "secret of the soul" in the milah, and the "secret of space" in Eretz Yisrael and the Bais HaMikdash — all part of the "great goodness hidden away for those who fear Him."