Nissan 30 is the yahrtzeit (anniversary of the passing) of the famed Kabbalist Rabbi Chaim Vital (1542?-1620), author of the mystical work Eitz Chaim. Rabbi Chaim was the leading disciple of Rabbi Isaac Luria (the "Holy Ari," 1534-1572) and the transcriber of his teachings, which form the "Lurianic" Kabbalah.

Links: About Kabbalah

Today is the first of the two Rosh Chodesh ("Head of the Month") days for the month of "Iyar" (when a month has 30 days, both the last day of the month and the first day of the following month serve as the following month's Rosh Chodesh).

Special portions are added to the daily prayers: Hallel (Psalms 113-118) is recited -- in its "partial" form -- following the Shacharit morning prayer, and the Yaaleh V'yavo prayer is added to the Amidah and to Grace After Meals; the additional Musaf prayer is said (when Rosh Chodesh is Shabbat, special additions are made to the Shabbat Musaf). Tachnun (confession of sins) and similar prayers are omitted.

Many have the custom to mark Rosh Chodesh with a festive meal and reduced work activity. The latter custom is prevalent amongst women, who have a special affinity with Rosh Chodesh -- the month being the feminine aspect of the Jewish Calendar.

Links: The 29th Day; The Lunar Files

Tomorrow is the sixteenth day of the Omer Count. Since, on the Jewish calendar, the day begins at nightfall of the previous evening, we count the omer for tomorrow's date tonight, after nightfall: "Today is sixteen days, which are two weeks and two days, to the Omer." (If you miss the count tonight, you can count the omer all day tomorrow, but without the preceding blessing).

The 49-day "Counting of the Omer" retraces our ancestors' seven-week spiritual journey from the Exodus to Sinai. Each evening we recite a special blessing and count the days and weeks that have passed since the Omer; the 50th day is Shavuot, the festival celebrating the Giving of the Torah at Sinai.

Tonight's Sefirah: Gevurah sheb'Tifferet -- "Restraint in Harmony"

The teachings of Kabbalah explain that there are seven "Divine Attributes" -- Sefirot -- that G-d assumes through which to relate to our existence: Chessed, Gevurah, Tifferet, Netzach, Hod, Yesod and Malchut ("Love", "Strength", "Beauty", "Victory", "Splendor", "Foundation" and "Sovereignty"). In the human being, created in the "image of G-d," the seven sefirot are mirrored in the seven "emotional attributes" of the human soul: Kindness, Restraint, Harmony, Ambition, Humility, Connection and Receptiveness. Each of the seven attributes contain elements of all seven--i.e., "Kindness in Kindness", "Restraint in Kindness", "Harmony in Kindness", etc.--making for a total of forty-nine traits. The 49-day Omer Count is thus a 49-step process of self-refinement, with each day devoted to the "rectification" and perfection of one the forty-nine "sefirot."

Links:
How to count the Omer
The deeper significance of the Omer Count