When Noach is warned of the impending flood, the first ever distinction is made between kosher and non-kosher animals. This was not practical dietary information yet, as humans were not yet permitted to consume meat. Yet there was still a certain degree of relevance to the people of the time – they were only allowed to bring sacrificial offerings from kosher animals.
When Noach is instructed how to populate the ark, he is to seek out the kosher animals, whereas the non-kosher animals would come to him. But why the distinction?
Kosher does not exist for bodily health.
Rabbi Samson Raphael Hirsch explains that animals are טהור if they are receptive to human influence; they are submissive to man without requiring to be tamed; they serve our purposes; their instincts do not overwhelmingly determine their behaviour. Animals which are not טהור are unable to be controlled, and can only be tamed, if at all, through violence.
The word for kosher animals, טהור, is related to the word צהור meaning transparent, which describes a property that allows light to pass through something. Consequently, purity has the implications of being conducive and receptive.
This same property is relevant to sacrifices. The main function of a sacrifice is to symbolically dedicate or actions to God. Through its blood, we symbolically devote our own lifeblood to God’s will. Accordingly, only animals which closely align to this disposition are suitable. The characteristics of the kosher animals are what Jews should aspire to have within them – a controlled instinct.
The animals designated as kosher inform humanity of our mission. Consequently, it is understandable why Noach was commanded to actively seek out the animals that showed the characteristic missing in his generation.
Moral consciousness is an active choice.