“There is no ‘earlier’ or ‘later’ in Torah,” states the Talmud, meaning that the events recounted by the Torah do not necessarily follow in chronological order of their occurrence. For Torah will often disregard the time-context of an event for the sake of an insight or lesson that can be derived from its appearance in proximity to earlier or later event or in a certain conceptual context.
The Talmud derives this rule from the Torah’s account of the origins of Pesach Sheini, the “Second Passover.” In the ninth chapter of Numbers, we read how “in the second year from the exodus from Egypt, in the first month” G-d commanded Moses that the Jewish people should offer the korban pesach (“pascal lamb”) as they did a year earlier, on the eve of the Exodus. The Torah goes on to relate that a group of Jews who were in a state of ritual impurity–a state which prevented them from participating in the Passover offering–approached Moses with the protest: “Why should we be deprived?!” We, too, cried they, desire to serve G-d by bringing a korban pesach, as the entire community will. In response to their cry, G-d instituted a “Second Passover”: beginning with that year, and for all future generations, a person who was ritually impure or on a “distant road” on Passover eve will be given the opportunity to do so one month later, on the fourteenth of Iyar.
As cited above, all this occurred in the first month of the second year from the Exodus. And yet, the Torah, for its own reasons, relates this event several chapters after its account–in Numbers 1-4–of the census the Jewish people that was taken on “the second month of the second year from the Exodus.” Hence the rule, “There is no earlier or later in Torah.”
Everything in Torah, and every detail thereof, is significant and instructive. The fact that the Talmud considers the case of the “Second Passover” to be the source of the principle that “There is no earlier or later in Torah,” although the Torah abounds with many demonstrable instances of this (Rashi cites one example as early as Genesis 6:3), implies that this particular case is intrinsically connected to this particular rule.
The eternal significance of the “Second Passover” is that there are no missed opportunities, that it is never too late to rectify a past failing. Even one whose compromised spiritual state (his “ritual impurity”), or his alienation from his people and G-d (his being “on a distant road”), have prevented him from fulfilling a certain aspect of his mission in life, there is always a second chance.
Therein lies the essence of teshuvah, Torah’s formula for the rectification of a deficient past. The term is commonly translated as “repentance,” but teshuvah is more than regret over and atonement for wrongdoing. “Repentance” implies only that, at most, a past misdeed will have no adverse effect on one’s present and future, but it cannot change the fact that, in the past, one has done wrong or has failed to achieve what might have been achieved. Teshuvah–the word literally means “return”–is the endeavor to undo and re-do the past, to transform prior failings into virtues and fill yesterday’s vacuums with content. The group of petitioners that approached Moses did not ask that they be excused for their inability to offer the korban pesach; they asked that they “not be deprived,” that they be accorded an opportunity to fulfill an aspect of their relationship with G-d whose appointed time had found them in a spiritual state that precluded their doing so.
Thus, the story of the “Second Passover” gives rise to the principle that “There is no earlier or later in Torah.” That a life lived by Torah is not subject to the tyranny of time, that for such a life, the past is no less replete with opportunity than the future.
 Talmud, Pesachim 6b.
 Talmud, Yuma 86b; Tanya, chapter 7.