שלח תשלח את האם ואת הבנים תקח לך למען ייטב לך והארכת ימים: כי תבנה בית חדש ועשית מעקה לגגך ולא תשים דמים בביתך כי יפל הנפל ממנו.” (דברים כ”ב, ח’)
רש”י: “אם קיימת מצות שלוח הקן סופך לבנות בית חדש ותקיים מצות מעקה, שמצוה גוררת מצוה, ותגיע לכרם ושדה ולבגדים נאים. לכך נסמכו פרשיות הללו
Rashi: “If you fulfilled the mitzvah of sending away (the mother bird from) the nest, your end will be to build a new house and fulfill the mitzvah of (building) a fence. Because a mitzvah draws another mitzvah after it, and you will arrive at (owning) a vineyard and a field and nice clothing. Therefore, these passages are juxtaposed.”
We typically understand the concept of “מצוה גוררת מצוה”—a mitzvah draws another mitzvah after it—in the sense that certain mitzvos are interrelated, and thus by fulfilling one mitzvah, we begin a process which leads to the fulfillment of another mitzvah. For example, if a person honors his or her parents, that might begin a process of gratitude which leads to bentching with more devotion and intent.
But there is more to it than that. I recall that as a young avreich in the Yeshiva in Be’er Yaakov, I participated one zman in a small vaad led by the Mashgiach zt”l, that grew smaller and smaller until I was the only talmid remaining. Still, I continued working on the subject of the vaad, when quite surprisingly, a whole new world of Avodah opened up before me, in an area that was completely unrelated to what I had been working on. When I mentioned this to the Mashgiach, he remarked that such is the nature of mitzvos: “מצוה גוררת מצוה”. This is an experience unique to mitzvos. If you study physics, you might gain a better understanding of engineering, but not of Shakespeare. If you put in extra hours of practice on the basketball court, you will not suddenly become a more talented pianist. But with mitzvos, you will discover entirely unexpected avenues for future Avodah.
The secret to this phenomenon lies in the Rashi above. “A mitzvah draws another mitzvah after it”, but apparently, not only does it lead to another mitzvah, but to a new house, vineyard, and clothing as well. Why is that a part of “מצוה גוררת מצוה”— is it some kind of bonus prize, like winning the Oorah raffle? Is it simply a technicality, that Hakadosh Baruch Hu cannot provide you with any new mitzvah opportunities without gifting you a new home or wardrobe? Of course not. The fundamental idea here is that mitzvos are not simply done and that’s all; they are meant to enrich one’s world. The Pesukim begin with someone who has no house, only that he finds an ownerless bird, nesting. Subsequently, he builds a house, which is a simple, basic necessity, and then he proceeds to acquire a vineyard. Afterwards he buys a field and animals to work the field, and then, even nice clothing. Throughout this progression, his world becomes broader and more refined. The mitzvos enrich his world, and thus he discovers new mitzvos, which enrichen his world even more, enabling him to fulfill even more mitzvos. The pesukim present this enrichment on a physical level, but it is likewise true on a spiritual level: the mitzvos enhance and broaden one’s spiritual world as well.
The phenomenon of “מצוה גוררת מצוה” is not due solely to the relationship between any two mitzvos, but rather because through the mitzvos, one’s reality changes and develops. And once a person finds himself in a new, broader reality, he discovers new possibilities in all different kinds of places. As such, a person who takes care to honor his parents properly might become more careful about kashrus, even though these mitzvos don’t seem to be related. His reality has changed; what was previously mundane takes on special meaning, and he recognizes things that he did not notice beforehand. A mitzvah draws another mitzvah after it because mitzvos have the potential to change our reality, creating new possibilities for Kedusha.