[30a bottom] R’ Yochanan ben Zakai: One may not eat new grains until the morning of the 17th when the Temple is standing. However [even though now-a-days it is Biblically permitted], people should not get used to eating on the morning of the 16th because when the Beis Hamikdash is rebuilt people might mistakenly eat from the new grains before the Omer sacrifice is offered [which is prohibited]. Therefore, Zacher Lamikdash (as a “remembrance” for the Temple] we enact this and many other decrees.
E’s Lesson: As we say in the Ani Ma’amins, we believe everyday that Moshiach will come. The Rabbis even went to such great lengths enacting decrees for us now on the chance that Moshiach would come literally today. We must keep this faith and hope on the forefront of our minds. R’ Nosson Wachtfogel zt”l always kept a packed bag and was constantly ready for when Moshiach would come! We must get our bodies and minds ready for the ultimate redemption and be ready for the birth of the redemption era, speedily in our days.