The month of Siwan is associated with the tribe of Zevulun. Zevulun,  a seafaring tribe, is associated with the chilazon, a little sea slug of which techelet was made, the blue of the blue thread in the tzitzit. The tzitzit reminds us of the mitzwot, the commandments. What is so exceptional about techelet? It was chosen above all other colours because it looked like the colour of the ocean, which resembled the colour of the sky, which was like the colour of the Throne of Glory that stood on a paving of sapphire. Chazal, that is chachamim zichronam livracha, our sages, may their memory be for a blessing, concluded from this that spiritual growth does not happen in one big step, but step by step, like the rungs of a ladder. On Sinai, our sages say, haShem bended the lower and the higher heavens and spread them over the mountain of Sinai during Matan Torah, the giving of the Torah. A kind of wormhole. But afterwards the heavens returned to their original positions, and we have to climb the ladder again to reach a higher level. Every day, step by baby step, we work on our spiritual elevation mechail el chail (Teh 84:7), from strength to strength.