There is a famous parable for Elul which compares it to a king strolling in his field, at which time anyone can approach him. This moshol is quoted as if it were a midrash; but in fact it is not. [There is a midrash that the Tur brings about a group of people preempting the king, by coming to him while he's travelling, but its intent is quite different.]. The true source of this moshol is the Baal Hatanya [Likutei Torah Reeh].
On the surface of it, the parable seems to not have much content. It is simply a somewhat vague metaphor for having easier access to the king. Why should we have easier access? Why don't we have to make an appointment with the king at his palace? What prompted the royal stroll in his field?
Let us take a closer look at the Baal Hatanya's words:
"Why are the yud gimmel middos revealed during Elul, though they are a very lofty revelation suitable primarily for Yom Kippur? One can compare it to a king who, before he arrives in the town, is accessible to everyone and is friendly with them. When the king proceeds to the city, they then follow him. Once he is in his palace they need permission to enter..."
I think that the words "they then follow him" are crucial to understand the moshol. Although one needs special permission to enter the palace, poor peasants are so far removed from the refinement of the monarchy that they lack any interest in even making an appointment to see the king. What does the king do to give them an inkling of what it means to meet him? He extends himself undeservedly to them, so that they gain some sense of what he is. When their interest is aroused, and their passions are excited, they follow the king to his palace. And now they must deserve to enter.
If you wish, this is actually a passuk in Shir Hashirim. In the fifth perek there is a description of the king's beloved having become tired of the king. He begs her to open the door, and she replies that she is tired and has gone to sleep. He then puts his hand through the keyhole, and she begins to yearn for him. But by that point he is gone, and she must spend the rest of her time pursuing him.
Hashem's availability in Elul has the same dynamic. A beloved has lost interest, and unless that interest is aroused again, she/he will never even bother to pursue the king. The Baal Hatanya's parable teaches us that in order for the process of din to be meaningful, a desire must first be aroused in the populace to achieve closeness to Hashem. Thus, Elul is a time when Hashem grants us an undeserved rush of spirituality. This is not real spirituality which can be achvied only through effort. This undeserved spirituality is meant to draw us out of our beds of comfort, and to entice us to begin following the king to his palace. Once we reach the palace, i.e. Yom Kippur, we must show ourselves deserving.