Back in the day, a measure of grain was brought to the Temple as an offering each day between the first of Pesach and Shavu'ot, seven weeks later. The measure, known as an omer, was waved over the altar and then used to sustain the priests. We are certainly mystified by the practice of wave-offerings, but we remember them nonetheless.
From the night of the second seder (which is the first day of chol hamo'ed in Israel) we commemorate the ancient Temple practice by counting the days and weeks until the arrival of Shavu'ot, seven full weeks. In an agricultural society, in a climate like the Holy Land, those seven weeks were among the most fecund of all. Crops sprouted, trees blossomed, plants took root. Almost every morning a transformation had taken place, and by the end of the festival period the first fruits were ready to be presented as their own offering in the Temple.
We only imagine those times now. Even those of us with our own backyard gardens have no idea of the miraculous nature of this annual period of uncertainty. Survival itself was dependent on the generosity of the soil and the trees, and the gratitude that farmers and consumers felt as spring eased into summer was palpable.
Today we find fruits out of season in the local supermarket — strawberries reaching market mid-winter and cherries before the bloom. Our experience is different but equally out of sync with our forebears in the Diaspora. They, too, were at a loss as to how to experience the period of the omer and the festival of first fruits at Shavu'ot. And though they could not put their fingers on what they had lost, they were still bereft. So they instituted the counting and a period of mourning for the lost offerings.
But our tradition, in spite of our history of suffering, was not willing to tolerate so much sadness. Adding up the number of days in the omer that it was forbidden to mourn — Shabbat, Rosh Chodesh, holidays — some simple subtraction designated the 33rd day as the day when our quota of grieving ended. Lag (33) Ba'omer became a day of fun and frolic.
And more: we refused to do without our harvest. Some creative reading of the Biblical text put our ancestors at the foot of Mount Sinai seven weeks after leaving Egypt. And that meant that Torah was revealed to us after that initial period of daily transformation in the wilderness — an occasion to celebrate many centuries later with a sense of gratitude we can appreciate.
A tree or a plant will not put forth an identical harvest each year, yet every apple and pod will bear the essence of the root and the seeds of renewal. Each year our ancestors offered the first fruits that were ancient and brand new at once. Our harvest is Torah. Should we do no less?