Knowledge that is rooted in clear, incontrovertible evidence can be relied upon and used, regardless of who discovered or formulated that knowledge.

The reason for all of these calculations, why we add this number [of minutes or hours to the month] or why we subtract, how we know each of these matters, and the proof for each of them, is [all based on] the wisdom of astronomy and geometry about which the wise men of Greece compiled many books and these are now in the hands of the Sages. But the books that the wise men of Israel, descendents of the tribe of Issachar, composed during the days of the prophets did not reach us. Since all of these matters have clear, conclusive, incontrovertible proofs, it is inconsequential whether these books were authored by prophets or gentiles. With regard to any matter whose reason is known and whose truth is confirmed through conclusive proofs, one is not relying on the particular individual who said or taught [this information], but rather upon the proof that has been discovered and the reason that has become known. (Rambam, Mishneh Torah, Hilkhot Kiddush HaĤodesh 17:24)

Further reading: For more on the mitzva of sanctifying the new month, see A Concise Guide to Halakha, p. 237.

People invest time and energy in attaining human wisdom. However, even those who study logic, mathematics, physics, astronomy, and music yearn to understand that which is beyond the physical world. Through Torah study, especially if one learns from a teacher who has been trained in the wisdom passed down by Jewish tradition, one can come to know much about the spiritual world and the divine.

It is clear that the primary benefit of other types of wisdom is only to serve as a stepladder to [Torah] and to the wisdom they call knowledge of the Creator. For when they spend their time studying logic so they will not make a mistake in their inferences, and then they come to [study] mathematics, including complex calculations and geometry, the benefit these [studies] provide is that one will be able to say the height of a wall or the depth of a pit. If they then move from these [studies] to astronomy, which has great benefit [in allowing one] to know the movements of the constellations, the closeness and distance [of the heavenly bodies to the earth], the inhabitable earth, and eclipses, the benefit still does not match the effort. If they move to the study of music, the effort is even greater and the benefit less. They themselves admit that the great benefit of all of these comes when they reach in their research the wisdom they call metaphysics, which is wisdom of the divine. They research and acknowledge incorporeal intellects, which are angels, and that there are different levels of them in existence, until they reach the Prime Cause, may His kingship be blessed and exalted, and they research how creations came from Him…. But a Jewish child has read more about creation [than these scholars], for he sees in the Torah what was created on the first day and what was created on the second day. If he analyzes this and thinks wisely about it, or [learns] from a teacher who has received the oral tradition, he will know that whatever comes first in creation is more fine and more lofty than what comes next, and he will derive the number of primary elements that exist. (Ramban, Torat Hashem Temima)

The natural sciences are the product of human thought and comprise a significant body of wisdom. Human wisdom can aid one to attain divine wisdom, and natural sciences can bring one to appreciate the greatness of God, who created the natural world. However, when scholars promote views that run counter to belief in God, one should pay no attention other than for the purpose of knowing how to respond effectively.

Natural sciences are fundamentally correct:

“If a person tells you, ‘There is wisdom among the nations,’ believe him” (Eikha Rabba, 2)…. These are the words of the Rambam in his work: Concerning whatever the scholars of the nations said about what is beneath the sphere of the moon, one should accept their [wisdom], for they were wise with regard to the natural world. But what they said about what is above the sphere of the moon, which goes beyond nature, one should not accept [their wisdom]. For they were wise concerning the natural world, but with regard to that which is above nature, which is divine wisdom, one should not listen to them (based on Guide of the Perplexed II:22). (Maharal of Prague)

Learning natural sciences is part of appreciating the greatness of the Creator, and leads to a deeper understanding of the Torah:

What they have formulated is bona fide wisdom, for there is no difference between Jewish wisdom and the wisdom of the nations…. Consequently, one should study the wisdom of the nations, for why should one not study wisdom that is from God, may He be blessed? It is illogical to say that although it is bona fide wisdom, one should not stray from the Torah, as it is written: “You shall ponder it day and night” (Joshua 1:8)…. For this wisdom is like a ladder upon which to ascend to the wisdom of the Torah…. For one should study anything that [aids one to] comprehend the nature of the world, and one is [even] obligated to do so, for everything is created by God and one should appreciate it and thereby recognize his Creator.

One should disregard human wisdom when it contradicts Jewish belief:

The principle that emerges from what we have written is that one should examine their words so that he can respond to them, to a questioner, as the Sages said (Mishna Avot 2:14). If he finds that they said something proper that strengthens belief, he should accept it. However, if he finds something, even a small thing, that contradicts Jewish belief or that [contradicts] anything said by the Sages, God forbid that he should listen to them. But he should think, in his mind, how to respond to their words according to his ability. (Netivot Olam, Netiv HaTorah, chap. 14)

Human wisdom can serve as an aid for Torah study, but only Torah is absolute, objective truth. One should engage in other areas of study from a Torah perspective. Torah and other subjects are not of equal value. Other subjects are human wisdom, whereas Torah is divine wisdom, the objective standard for all other areas of study.

All types of wisdom can serve as aids to Torah study:

Torah is primary and absolute. This does not mean that we should refrain from gaining any exposure to other realms, but we must make these secondary to Torah study. The Torah is the yardstick [by which we assess] them. God’s Torah is the sole authority, whereas the others are human wisdom, and are therefore imperfect…. We should consider that which we learn from the Torah to be absolute fact. Other areas of wisdom should be merely auxiliary. One should engage in their study only if they can aid his study of Torah and they are viewed as secondary to the primary [goal of Torah study]. The truth of Torah should be to us an unconditional axiom.

The Torah is the point of departure, and the yardstick by which to measure other disciplines:

Our sole focus should be [Torah. In this way,] whatever we absorb or create in the spiritual realm will be from a Torah perspective. We will not absorb things that are inconsistent with it, and we will not accept things that emerge from a different set of assumptions and mix them with Torah. The Torah should not be considered equal to other disciplines, as though it is one discipline among many others. It should not enter one’s mind that there is Jewish wisdom and truth, and along with it, with the same degree of authority and importance, there is non-Jewish wisdom and truth…. Just as we are certain that the Torah is from Heaven and disciplines developed by mankind are just the wisdom of the human mind, and they include conclusions based on one’s limited understanding of nature, so too, we are certain that there is only one truth, and one discipline that serves as our yardstick by which to measure all else. (Rabbi Samson Raphael Hirsch, Commentary on the Torah, Leviticus 18:4)

A Jew may study the wisdom of the nations only in order to be able to earn a good livelihood, or if he knows how to use this knowledge in the service of God. Otherwise, such involvement constitutes a sin of neglecting Torah study. It is even worse than other manners of neglecting Torah study, as it defiles the intellectual aspect of a Jew’s divine soul.

One who studies the wisdom of the nations is considered to be engaged in idle chatter [and thereby violates] the sin of neglecting Torah study, as we stated in Hilkhot Talmud Torah (3:7). Moreover, the impurity of the wisdom of the nations is even greater than the impurity of idle chatter. [The latter] envelops and defiles only the emotional attributes [that stem] from the holy element of air within the divine soul, with the impurity of kelipat noga (the glowing husk) associated with idle chatter, which derives from the evil element of air within this kelipa (husk) of his animal soul, as stated previously. [The idle pursuits] do not defile the aspect of his soul’s wisdom-understanding-knowledge, [i.e., the intellect], since these are foolish and boorish matters that fools and ignoramuses can also speak of. However, the wisdom of the nations envelops and defiles also the aspect of his divine soul’s wisdom-understanding-knowledge with the impurity of the kelipat noga…. [Engaging in this wisdom is permitted] only if it is utilized as an instrument to earn a gainful livelihood, enabling him to serve God, or if he knows how to apply it to the service of God or His Torah. This is the reason Rambam and Ramban, and their peers, studied this [wisdom]. (Rabbi Shneur Zalman of Liadi, Tanya, Likutei Amarim, chap. 8)

Exposure to human wisdom can lead a person to heresy. Consequently, only a righteous person, whose faith is strong, can and must be involved in [pursuing] human wisdom.

In truth, it is a great prohibition to be a philosopher, God forbid, and to study books of [human] wisdom, God forbid. Only a very righteous individual can begin to study the seven types of wisdom, for one who enters these types of wisdom can fall, God forbid. For each and every type of wisdom has a stumbling block, an expression of [the spiritual legacy] of Amalek, and through that stumbling block one can fall, God forbid. Amalek was a philosopher and an intellectual and he denied God, as it is written: “He [Amalek] was not God-fearing” (Deuteronomy 25:18). He conducted himself based only on [human] wisdom and did not fear God at all. But when the righteous individual enters [the study of] these seven types of wisdom he steadies himself and stays secure in his position through faith, an expression of the verse: “The righteous will live by his faith” (Habakkuk 2:4). (Rabbi Naĥman of Breslov, Likutei Moharan 2:19)