Shelach - Sh'vi'i
The Gatherer and Tzitzis
If an individual accidentally commits an act of idolatry, he is to bring a goat as a sin offering. Again, he will be forgiven because it was a mistake. But if someone worships an idol intentionally, it's an act of blasphemy against G-d and the idolator will be spiritually cut off from the nation.
One Shabbos, a man insisted on gathering firewood, which is prohibited for a variety of reasons. G-d had already indicated that the penalty was death, but He had not specified which manner of execution was to be used, so the "mekosheish" (gatherer) was placed under guard until G-d gave Moshe specific instructions. It turned out that the penalty was stoning and the people acted on this directive. (According to the Talmud in Shabbos 96b, the mekosheish was Tzelofchad. We'll hear more about him in parshas Pinchas, chapter 27.)
Finally, G-d commanded that tzitzis (usually rendered "fringes," but really more like tassels) be attached to four-cornered garments in perpetuity. One of the eight strings on each corner would be dyed a special shade of blue called techeiles. These strings would serve as a constant reminder of G-d's commandments, helping to keep people on the straight and narrow. (This is what happened in a famous story in Talmud Menachos 44a.) We still wear tzitzis today, though we've lost the special techeiles, which was a dye produced from a mollusk called the chilazon in Hebrew (Menachos 44a again). Some feel that this dye has been rediscovered, but this is far from universally acknowledged.