Small Lapses Breed Great Sins
במדרש איכה אשא לבדי איכה היתה לזונה איכה ישבה בדד כו'
In the Midrash on Eichah: "How shall I bear it by myself" (Devarim 1:12), "How has she become like a harlot" (Yeshayahu 1:21), "How does she sit in solitude" (Eichah 1:1), and so forth.
The Midrash links three verses that each open with the word "Eichah" (How), drawn from Devarim, Yeshayahu, and Eichah. They mark three stages in the relationship between Hashem and Bnei Yisrael.
ג' שראו המטרונה בשלוותה ובפחזותה ובנוולותה
There were three who beheld the queen: in her tranquility, in her recklessness, and in her degradation.
These three "Eichah" verses correspond to three figures who saw the queen — a mashal for Klal Yisrael — at three different points: in her flourishing, in her wild straying, and finally in her ruin.
הענין הוא דכל החטאים שבכלל ישראל הי' קצת מהם בשורש דורות הראשונים
The matter is that all the sins found within the general body of Bnei Yisrael had some of their root already in the earlier generations.
The Sfas Emes explains that every sin that later appeared in Bnei Yisrael had some seed of its origin already present in the earliest generations.
דכמו כל הזכותים של בנ"י הם מאבותיהם
For just as all the merits of Bnei Yisrael come to them from their forefathers,
Just as the spiritual merits of Bnei Yisrael are inherited from the Avos,
כן אם הי' תיקון גמור בשורש לא הי' נצמח החטאים אח"כ
so too, had there been a complete rectification at the root, the sins would not have sprouted forth afterward.
so too the reverse is true: had the root been fully repaired, no later sins could have grown out of it.
וז"ש אבותינו חטאו ואינ' ואנחנו עוונותיהם סבלנו
And this is the meaning of "Our fathers sinned and are no more, and we have borne their iniquities" (Eichah 5:7).
This is the meaning of the verse in Eichah: the fathers sinned, and the later generations bore the weight of those iniquities that grew from the original flaw.
פי' כי חטא קל מעון כמ"ש שגגות הם חטאים וזדונות עונות
The explanation is that a chet (sin) is lighter than an avon (iniquity), as it is written that "shegagos" (inadvertent transgressions) are called chataim, while "zedonos" (willful transgressions) are called avonos.
A chet is a lesser transgression than an avon; a chet is inadvertent (shogeg), while an avon is willful (meizid). The earlier flaw began as the lighter kind.
וע"י השוגג שבאבותינו נצמח אח"כ בדורות אחרונים זדונות
And through the inadvertent transgression that lay in our forefathers, there sprouted forth afterward, in the later generations, willful transgressions.
The small, inadvertent failing in the forefathers became the root from which willful, deliberate sins later sprouted in the descendants.
דכמו עבירה גוררת עבירה ומתחיל כחוט ומסיים כעבות העגלה
For just as "one aveirah drags another aveirah after it," and it begins like a thin thread and ends like the thick rope of a wagon,
Chazal teach that one aveirah pulls another after it; the yetzer hara starts as a thin thread but grows into a thick rope binding a person.
כן בכלל אם יש בדורות ראשונים שגגות ועבירות קלות נמשך אח"כ חטאים גדולים
so too, in general, if among the earlier generations there are inadvertent transgressions and minor aveiros, great sins are drawn forth afterward as a consequence.
On a national scale the same dynamic holds: minor, inadvertent transgressions in the early generations draw forth grave sins in the later ones.
כמו כן בזה מ"ש איכה אשא לבדי שלא הי' ניכר חטאם בפועל רק שלא היו נמשכים אחר הנהגת מרע"ה וזה הביא אח"כ איכה היתה לזונה כו' וכמ"ש בשם בעש"ט וסרתם בא אח"כ ועבדתם אלהים אחרים וזה נאמר על גדולי עולם כאלה:
Likewise, this is the meaning of "How shall I bear it by myself" (Devarim 1:12) — that their sin was not yet discernible in actual deed; it was only that they were not drawing themselves after the leadership of Moshe Rabbeinu, and this is what brought about afterward "How has she become like a harlot" (Yeshayahu 1:21), and so forth. And as it is said in the name of the Baal Shem Tov, "and you will turn aside" (Devarim 11:16) comes first, and afterward "and you will serve other gods" — and this was said regarding such great ones of the world as these.
The first "Eichah" — "How shall I bear it by myself" — reflects the earliest, barely visible flaw: Bnei Yisrael merely failed to fully attach themselves to Moshe Rabbeinu's leadership. That subtle lapse eventually grew into the open betrayal of "How has she become like a harlot." The Baal Shem Tov reads the Torah's sequence the same way — first a slight turning aside, then full-blown avodah zarah — and this warning applies even to the greatest spiritual giants.
Summary: The Sfas Emes builds on the Midrash that connects three verses opening with "Eichah," which trace Klal Yisrael's descent from tranquility to recklessness to ruin. His central point is that every later sin had its root already planted in the earliest generations: just as the merits of Bnei Yisrael are inherited from the Avos, so a sin left unrectified at the root eventually sprouts into something far worse. He distinguishes between a chet — a light, inadvertent failing — and an avon, a willful transgression, and explains that the inadvertent lapses of the forefathers grew, generation by generation, into deliberate sins, for one aveirah drags another and begins like a thin thread but ends like a thick rope. The first "Eichah" was thus not an open sin at all, but only a failure to fully follow the leadership of Moshe Rabbeinu — yet that subtle distance is what ultimately led to the harlotry of "How has she become like a harlot." Citing the Baal Shem Tov, he warns that even the greatest tzaddikim must guard against the smallest turning aside, since it is from such small beginnings that the gravest falls eventually grow.