In the Bhagavad-gītā it is clearly explained that there are three kinds of activities according to the different modes of nature: the activities of goodness, of passion and of ignorance. Similarly, there are three kinds of eatables also: eatables in goodness, passion and ignorance. All of this is clearly described, and if we properly utilize the instructions of Bhagavad-gītā, then our whole life will become purified, and ultimately we will be able to reach the destination which is beyond this material sky (yad gatvā na nivartante tad dhāma paramaṁ mama). (BG 15.6)
That destination is called the sanātana sky, the eternal, spiritual sky. In this material world we find that everything is temporary. It comes into being, stays for some time, produces some by-products, dwindles and then vanishes. That is the law of the material world, whether we use as an example this body, or a piece of fruit or anything. But beyond this temporary world there is another world of which we have information. That world consists of another nature, which is sanātana, eternal. Jīva is also described as sanātana, eternal, and the Lord is also described as sanātana in the Eleventh Chapter.