Holding fast to first inspiration

ויעש כן אהרן.

"And Aharon did so" (Bamidbar 8:3).

The verse describes Aharon kindling the Menorah exactly as commanded; the Sefas Emes will explore what "and he did so" is coming to praise.

שלא שינה.

"That he did not deviate" (Rashi).

Rashi explains the praise of "and Aharon did so" as telling us that Aharon did not change anything — he carried out the mitzvah precisely as he was commanded.

יש לפרש כי עשה מעשה המצוה כל ימי חייו בכוונה ורצון אחד.

It can be explained that he performed the act of the mitzvah all the days of his life with one [unchanging] intention and desire.

The Sefas Emes reads "he did not deviate" on a deeper level: Aharon kindled the Menorah with the same fresh kavanah and ratzon every single day, for his entire life — his enthusiasm never waned or grew stale.

כי דרך כל אדם.

For it is the way of every person —

The Sefas Emes now contrasts Aharon with the normal human pattern.

שבהתחלה מתעורר לטוב.

that at the beginning he is aroused toward the good,

People typically feel a strong initial hisorerus (awakening), an enthusiasm for a mitzvah or a path of avodah when they first begin.

אח"כ נשכח ממנו.

but afterward it is forgotten from him,

Over time that initial fire fades and the inspiration is lost, and the avodah becomes routine.

וצריך לחפש התעוררות באופן אחר תמיד.

and he must constantly seek arousal in a different manner.

To stay engaged, the ordinary person must keep searching for new techniques and fresh angles to re-ignite his motivation.

והאמת כי ההתפעלות הראשון הוא המובחר לזאת נאמר על אהרן שלא שינה וממילא בא לו תמיד השגות חדשות כמ"ש אם שמוע בישן תשמע בחדש:

But the truth is that the first arousal is the choicest one; therefore it is said of Aharon that "he did not deviate" — and as a result, new attainments came to him continually, as it is said, "If you will surely hearken" — if you hearken to the old, you will hear something new.

The original burst of inspiration is actually the purest and most precious. Aharon's greatness was that he held fast to that very first enthusiasm without changing it — and precisely because he stayed loyal to the "old," he was constantly granted new insights and revelations. This is the meaning of "if you hearken [to the old], you will hear [the new]": faithfully revisiting the original kavanah is what generates fresh spiritual attainment.

Summary: Aharon's praise that "he did not deviate" means he kindled the Menorah with the very same fresh kavanah and enthusiasm every day of his life. Whereas most people's initial inspiration fades, forcing them to chase ever-new forms of arousal, Aharon clung to that first, choicest hisorerus — and precisely through this loyalty to the "old," he merited continual new attainments, as in "if you hearken to the old, you will hear the new."