God tells Israel at Sinai, "And now, if you hearken to My voice" (Exodus 19:5). The Mekhilta highlights the word "now" — take it upon yourselves now, because all beginnings are difficult. The hardest part of any commitment is the first step. God acknowledged that what He was asking would not be easy, and He asked the people to begin while the moment was ripe, while the experience of revelation was fresh and their hearts were unified.
Then the Mekhilta turns to a striking grammatical feature of the Hebrew. The verse uses a doubled verb: "im shamoa tishma'u" — literally, "if hearken you shall hearken." This doubling is not mere emphasis. The rabbis derive from it a principle about the nature of spiritual momentum.
If a person hearkens to one mitzvah — if they truly listen and obey a single commandment — they are caused to hearken to many mitzvot (commandments)h. Obedience builds on itself. One commandment fulfilled leads to another, then another, creating a chain of increasing devotion. The doubled verb implies a multiplying effect: listening leads to more listening.
But the reverse is equally true, and equally powerful. If a person forgets one mitzvah — if they let a single commandment slip from their practice — they are caused to forget many mitzvoth. Neglect also compounds. A single omission opens a gap, and through that gap, other commandments begin to fall away.
The Mekhilta presents spiritual life as a system of momentum rather than isolated choices. Every individual act of obedience or neglect sets a trajectory. The Torah's doubled language captures this perfectly: hearing leads to hearing, and forgetting leads to forgetting. There is no standing still.