Judaism teaches that from the time of Pesach (Passover), until the time of Shavuot (Pentecost) the Jews shall count. This fifty day period is a time of preparation from the time that the Jews were freed from slavery in Egypt until they receive the Torah at Mount Sinai. During this time, a nation that had just emerged from long slavery and oppression prepared themselves physically, psychologically, and spiritually for the great event that would unify them as a nation.
All indications point to the Omer being a joyous period. The original days of the Omer, immediately after the exodus out of Egypt were days of festivity and celebration of the unification of a nation and the receiving of the Torah.
The mournful aspect of the Omer came in two stages: With the destruction of the Temple and the tragic deaths of the students of Rabbi Akiva, the great bible scholar. The Talmud teaches that they perished because they didn’t treat each other with respect. It is said that the students of Rabbi Akiva “stopped dying” on the 33rd day.
This raises the question: why celebrate when the students of Rabbi Akiva stopped dying, if they were all gone? The suggested answer is that this represents the hope for the future, that Torah learning and scholarship has not ended with their deaths.
Another aspect of joy on this day is the celebration of Rabbi Shimon Bar Yochai, who was forced into hiding, in order to learn Torah during the time of the Roman rule over the Land of Israel. His dedication to bible study in all areas show us the great potential, that literally defines living for the bible. Lag BaOmer is his yahrzeit (the day he died) so many use this day as a time to reflect on his life and accomplishments, and his continuous dedication to grow in learning and prevalence to rebuild the Temple.
Lag BaOmer falls on the 18th day of the month of Iyar. Lag BaOmer stands out as a bright day in contrast to the mournful period of the Omer. It represents the bright promise of the future.