To give is to receive. You shall tithe all the produce of your fields. Not so, says the Torah. Not too unreasonably many people expect that Heaven reward them immediately, or at least with all deliberate speed, for their good deeds. Behold I give you this day a blessing and a curse.
Man becomes a better person through good deeds and less worthy through bad deeds.
The blessing of observing mitzvos lies in the observance proper, in man's striving and progressing toward a goal and ideal above himself. The curse of rejection of mitzvos is the debasement of man, his turning away from the path of righteousness. A holy people. In this Parsha, Moshe cautions the Jewish people again about many observances commanded by Hashem, including the laws of Kashrus. Many popular explanations have emerged for Kashrus.