Eretz Yisrael Revealed Light

במדרש כי אתם באים כו'

In the Midrash on the verse "For you are coming (into the land)...".

The Sfas Emes opens by citing a Midrash on the verse describing Bnei Yisrael coming into the land.

הדור אתם ראו כו' אם ארץ מאפלי' כו' דבאמת כל הארצות הם ארץ מאפליה

"This generation — see (the word of Hashem)... is the land a darkness..." (Yirmiyahu 2:31) — for in truth all the other lands are a "land of darkness".

He brings the verse from Yirmiyahu where Hashem rebukes the generation, asking whether He has been to them a "land of darkness" — and he reads it to mean that all lands outside Eretz Yisrael are indeed places of spiritual darkness.

אבל ארץ ישראל בחי' אור והרוחניות מתגלה בא"י ויוכל האדם להתדבק בשורשו, וז"ש זאת הארץ אשר תפול שראו בעין שורש קדושת ארץ ישראל ולכן זה מיוחד לבנ"י שהנפשות שלהם ג"כ מאירים ואין הגוף מסתיר הארת הנשמה ולכן א"י ראוי' לכם

But Eretz Yisrael is in the aspect of light, and the spiritual dimension becomes revealed in Eretz Yisrael, so that a person is able to cling to his root. And this is what is meant by "This is the land that shall fall (to you as an inheritance)" — that they beheld with their very eyes the root of the kedushah of Eretz Yisrael; and therefore it is uniquely set apart for Bnei Yisrael, for their neshamos likewise shine, and the body does not conceal the radiance of the neshamah, and therefore Eretz Yisrael is fitting for you.

Eretz Yisrael, by contrast, is a place of light where spirituality is openly revealed, allowing a person to attach himself to his spiritual root; Bnei Yisrael are suited to it because their neshamos shine and their bodies do not block that inner radiance.

ולכן עתה שאין הנפשות מתוקנים כראוי אין זוכין לארץ ישראל:

And therefore now, when the neshamos are not set in order as they ought to be, we do not merit Eretz Yisrael.

He concludes that nowadays, when our neshamos are not properly refined, we are not zocheh to actually possess Eretz Yisrael.

Summary: The Sfas Emes contrasts Eretz Yisrael with all other lands, which he calls a "land of darkness" based on the verse in Yirmiyahu. Eretz Yisrael alone is a place of revealed light, where the spiritual dimension shines forth and a person can cling to his true root. This is why the land is uniquely fitting for Bnei Yisrael, whose neshamos themselves radiate light such that the body does not obscure the glow of the neshamah. When Bnei Yisrael behold the land, they perceive with their very eyes the root of its kedushah. He concludes that in our times, when our neshamos are not properly set in order, we are unable to merit Eretz Yisrael.