A naturalist can see the general course of material nature simply by studying a piece of fruit. A small fruit develops from a flower, grows, stays for some time on a branch, becomes full-grown, ripens, then begins to dwindle daily until it finally falls from the tree and commences to decompose into the earth and at last mingles with the earth, leaving behind its seed which in its turn grows to become a tree and produces many fruits in time, which will all meet the same fate, and so on and so on.
Similarly, a living being (as a spiritual spark, a part of the Supreme Being) takes its organic form in the womb of a mother just after sexual intercourse. It grows little by little within the womb, is born, then continues growing, becomes a child, boy, youth, adult, old man, then finally dwindles and meets death, despite all the good wishes and hopeful pipe dreams of fiction writers. By comparison, there is no difference between man and the fruit. Like the fruit, the man may leave behind him his seeds of numerous children, but he cannot exist eternally within his material body due to the law of material nature.
How can anyone ignore the law of material nature? No material scientist can change the stringent laws of nature, however boastful he may be. No astronomer or scientist can change the course of the planets—he can only manufacture a paltry toy planet which he calls a satellite. Foolish children may be impressed by this and may give a great deal of credit to the inventors of modern satellites, sputniks, etc., but the saner section of humanity gives more credit to the creator of the gigantic satellites, namely the sun, stars and planets of which the material scientist can see no end. If a small toy satellite has a creator in Russia or America, it is reasonable that the gigantic satellites have their creator in the spiritual sky. If a toy satellite requires so many scientific brains for its manufacture and its orbiting, what kind of subtle and perfect brain created galaxies of stars and maintains them in their orbits? Thus far the atheistic class have not been able to answer this.
Nonbelievers put forward their own theories of the creation, which usually result in statements such as, "It's hard to understand," "Our imagination cannot conceive it, but it's quite possible," "It's incomprehensible," and so forth. This only means that their information has no authoritative basis and is not backed by scientific data. They simply speculate. However, authorized information is available in the Bhagavad-gītā. For instance, the Bhagavad-gītā informs us that within the material world there are living beings whose duration of life covers 4,300,000 x 1,000 x 2 x 30 x 12 x 100 solar years. We accept the Bhagavad-gītā as authority because this book of knowledge was so accepted by India's great sages like Śaṅkarācārya, Śrī Rāmānujācārya, Śrī Madhvācārya and Śrī Caitanya Mahāprabhu. The Bhagavad-gītā indicates that in the material world all component forms are subject to decay and death, regardless of their duration of life.
Therefore all material shapes are subject to the law of change, although potentially the material energy is conserved. Potentially, everything is eternal, but in the material world matter takes shape, remains for some time, develops into maturity, grows old, begins to dwindle and at last disappears again. This is the case with all material objects. The materialist's suggestion that beyond the material sky there is "some other form" which is beyond the boundary of visibility and which is strange and inconceivable is but a faint indication of the spiritual sky. However, the basic principle of spirit is much closer—for it functions within all living beings. When that spiritual principle is out of the material body, then the material body has no life. Within the body of a child, for instance, the spiritual principle is present, and therefore changes take place in the body and it develops. But if the spirit leaves the body, the development stops. This law is applicable to every material object. Matter transforms from one shape to another when it is in contact with spirit. Without spirit there is no transformation. The entire universe develops in that way. It emanates from the energy of the Transcendence because of the spiritual force which is His, and it develops into gigantic forms like the sun, moon, earth, etc. There are fourteen divisions of planetary systems, and although they are all different in dimension and quality, the same principle of development holds true for all. The spiritual force is the creator, and by this spiritual principle only, transformation, transition and development take place.
Life is definitely not generated simply by a material reaction like a chemical combination, as many foolish men claim. Material interaction is set in motion by a superior being who creates a favorable circumstance to accommodate the spiritual living force. The superior energy handles matter in an appropriate way—as determined by the free will of the spiritual being. For example, building materials do not automatically "react" and suddenly assume the shape of a residential house. The living spiritual being handles matter appropriately by his free will and thus constructs his house. Similarly, matter is the ingredient only, but the spirit is the creator. Only a man with a poor fund of knowledge avoids this conclusion. The creator may remain unseen in the background, but that does not mean that there is no creator. One should not be illusioned simply by the gigantic form of the material universe. Rather, one should learn to discern the existence of supreme intelligence behind all these material manifestations. The Supreme Being, who is the supreme intelligence, is the ultimate creator, the all-attractive Personality of Godhead, Śrī Kṛṣṇa. Although one may not be aware of this, there is definite information of the creator given in Vedic literatures such as the Bhagavad-gītā and especially the Śrīmad-Bhāgavatam.