"Tu" (the Hebrew abbreviation of 15th) in the month of Shvat was set (Hillel's opinion generally overrules Shammai's) as the beginning of the tithable year for tree fruit: Calculating the tithe on fruit starts again for fruit that sets after that date.
Here is the quintessential Jewish question: How do we emulate God? We are told that we were created by God. We are told that we have a divine spark within us.
It is life we want, no more and no less than that, our own life feeding on our own vital sources, in the fields and under the skies of our homeland, a life based on our own physical and mental labors; we want vital energy and spiritual richness from this living source.
Tu BiShvat (Jewish Arbor Day) is the time of year when Israeli schoolchildren plant trees. Perhaps it’s no coincidence that a teacher instituted the tree-planting custom.