The author does not cite any sources for this statement here. However he writes a similar idea in another work, “The Infinite Light”:
"Both man and nature have purpose because they were created by a purposeful Being. We call this Being G-d."To support this statement there the author cites Yad, Yesodey HaTorah 1:1-5 who writes:
1:1 The foundation of all foundations and the pillar of wisdom is to know that there is a Primary Being who brought into being all existence. All the beings of the heavens, the earth, and what is between them came into existence only from the truth of His being.An important point is that everything in creation, all of nature, has a purpose simply because it was created by G-d. Although not cited by our author a possible source for this could be the Gemara in Shabbos 77b:
1:2 If one would imagine that He does not exist, no other being could possibly exist.
1:3 If one would imagine that none of the entities aside from Him exist, He alone would continue to exist, and the nullification of their [existence] would not nullify His existence, because all the [other] entities require Him and He, blessed be He, does not require them nor any one of them. Therefore, the truth of His [being] does not resemble the truth of any of their [beings].
1:4 This is implied by the prophet's statement [Jeremiah 10:10]: "And God, your Lord, is true" - i.e., He alone is true and no other entity possesses truth that compares to His truth. This is what [is meant by] the Torah's statement [Deuteronomy 4:35]: "There is nothing else aside from Him" - i.e., aside from Him, there is no true existence like His.
1:5 This entity is the God of the world and the Lord of the entire earth. He controls the sphere with infinite and unbounded power. This power [continues] without interruption, because the sphere is constantly revolving, and it is impossible for it to revolve without someone causing it to revolve. [That one is] He, blessed be He, who causes it to revolve without a hand or any [other] corporeal dimension.
Rav Yehuda said in the name of Rav:
"In all that the Holy One, Blessed is He, created in His world He did not create even one thing needlessly."Rav Yehuda gives examples explaining the purpose of the slug, the fly, the gnat, the snake and even the spider. Similarly, there is a well known (though hard-to-find) midrash (Midrash Alpha Beta Acheres d'Ben Sira, 9) which states that King David felt he understood the purpose of everything in creation except for a very few things, one of them being the spider. Then on one occasion, while fleeing from King Saul, David ran into a cave. A spider quickly came along and wove a web over the entrance. Saul, seeing an undisturbed web, concluded that no one had entered the cave and went off. David, after realizing what had happened, humbly corrected his misconception.