Sir Isaac Newton formulated the laws of motion and described gravitation, the basic principle of physical world. Newton is considered as one of the most intelligent persons of all times. In 2005 when the scientists of British Royal Society were asked who made the bigger overall contribution to science 86 % of them chose Newton.
Newton described the laws of physical motion but was not able to explain what the cause of this motion is. In his own words "spirit" may be the cause of all movement in nature, including the "power of moving our body by our thoughts."
Science still has no rational explanation of the relationships of the so called material and spiritual world; moreover there is no consent among the scientists whether the division between material and spiritual is real. For example Bernard Russell did not believe in the reality of this dualism. We cannot argue that something is real, in this case "the spirit," if we cannot measure it. So if we hold the idea of existence of spiritual and material world we are not anymore "scientists" but "mystics."
Yet in science the speculations and hypotheses are permitted, even the "ridiculous" ones. So we can say without any hard evidence that the spirit exists, we can not measure him as we measure the matter and so we will never have the necessary "hard" evidences which are at disposal for explaining the laws of material world, but as it is written in the Bible, we can recognize him (the Spirit) through his work.
For example, there is a distinction between "spirit" (or "mind") and "instinct." With his achievements the spirit or mind, call him as you want, has a divine nature - the complicated character of modern state; the existence of legal systems; the creation of enormous buildings and megastructures; the science itself - everything that is born by the human mind and knowledge can be explained with the spirit, not with the instinct. The instinct directs our body and actions immediately. It is a reaction of the needs of our physical body - we are hungry, we are thirsty, it is hot or cold, we feel a danger for our life or sexual attraction.
With the instinct we react mechanically, but also very often with the help of the spirit. Very often we submit the spirit under the dictatorship of our instincts - and then we feel irrational emotions, we speak evil, we feel fear, we waging wars, and we create injustice. Often we use the powerful, divine spirit as a mighty weapon in blind hands.
Spinoza is the philosopher who
successfully differentiated the spirit from emotions (or the instincts); for him the emotions are an expression of physical. (See Ethics)
The instincts are immediate mechanical reflexes for defense of our body; they serve our basic physical needs and in their proper function they are not evil. The instinct is like the grammar in the language - it is indispensable, but with limited function.
The spirit is something that creates, he directs our body to do things that are still not visible, and he has a "prophetic" nature because he works for the future. In the New Testament was written that we have to wish the talent of prophecy. (Corinthians, 14:1-3: "Follow the way of love and eagerly desire spiritual gifts, especially the gift of prophecy...
But everyone who prophesies speaks to men for their strengthening, encouragement and comfort.")
While some scientists believe that the spirit exists they are not able to understand how he inhabits and arises from our physical body. Whether the brain is only machine conducting our body (a physical center of the instincts) or it is something more that is the sole source of spirit? Is the mind equal to the brain?
What is the physical cause for gravity or, to say, mathematics? How the neurons create language? Is it true that the mental is neurophysical at a higher level?
If we assume that the spirit exists so we can say that the language, the word, is his uppermost expression. The language is the tool that materializes the inexplicable forces of our spirit. We can not know the spirit without language. And we can not be humans without our complex communication with signs. Through the language we accumulate knowledge, experience, and trough the language we create knowledge and experience. Language can be used for good and for evil. And as it is written it turns the wheel of the life. (see James 3:1-12)
Neuroscientists do not understand how the nervous system creates the language, this system of signs and meaning. Mathematics and language are self developing systems; once their basis is created, it can be developed by its own logic. Mathematics and language - these are not material systems. And they exist. And nobody calls them "material." Nobody has doubts that they are non-material. And, yes, they hardly exist without the material presence of the sign. But nobody messes up the essence of mathematics and language, and it is not material.
Newton's analytical physics has no the ambition to explain the spiritual world. It is science describing the movement of material bodies. Why they move, what is the "subtle force" that causes this movement, what is the goal of this movement, are questions that have no answers. Many of the thinkers of Enlightenment knew the limits of human understanding although they were making a revolution in human knowledge. The brightest minds of contemporary world know that the human understanding has limits that are mobile. But one thing can be understood well by everybody - the earth's gravitation has no power over humans, because of our mind and spirit.
Notes from Spinoza's "OF HUMAN BONDAGE OR THE STRENGTH OF THE EMOTIONS" :
An emotion can only be controlled or destroyed by another emotion contrary thereto, and with more power for controlling emotion.
No one can desire to be blessed, to act rightly, and to live rightly, without at the same time wishing to be, to act, and to live--in other words, to actually exist.
To act absolutely in obedience to virtue is in us the same thing as to act, to live, or to preserve one's being (these three terms are identical in meaning) in accordance with the dictates of reason on the basis of seeking what is useful to one's self.
Whatsoever we endeavour in obedience to reason is nothing further than to understand
The mind's highest good is the knowledge of God, and the mind's highest virtue is to know God.
A thing cannot be bad for us through the quality which it has in common with our nature, but it is bad for us in so far as it is contrary to our nature.
In so far as men are a prey to passion, they cannot, in that respect, be said to be naturally in harmony.
The good which every man, who follows after virtue, desires for himself he will also desire for other men, and so much the more, in proportion as he has a greater knowledge of God.
Hatred can never be good.
He, who lives under the guidance of reason, endeavours, as far as possible, to render back love, or kindness, for other men's hatred, anger, contempt, &c., towards him.
Emotions of hope and fear cannot be in, themselves good.
Extreme pride or dejection indicates extreme infirmity of spirit.
The proud man delights in the company of flatterers and parasites, but hates the company of the high-minded.
Desire arising from a pleasure or pain, that is not attributable to the whole body, but only to one or certain parts thereof, is without utility in respect to a man as a whole.
Desire which springs from reason cannot be excessive.
He who is led by fear, and does good in order to escape evil, is not led by reason. (Because the fear cannot be equal to reason, and nobody can be led simultaneously by reason and fear)
Under the guidance of reason we should pursue the greater of two goods and the lesser of two evils.
We may, under the guidance of reason, seek a greater good in the future in preference to a lesser good in the present, and we may seek- a lesser evil in the present in preference to a greater evil in the future.
A free man thinks of death least of all things; and his wisdom is a meditation not of death but of life.
If men were born free, they would, so long as they remained free, form no conception of good and evil.
The free man, who lives among the ignorant, strives, as far as he can, to avoid receiving favours from them.
Only free men are thoroughly grateful one to another.
The free man never acts fraudently, but always in good faith.
The man, who is guided by reason, is more free in a State, where he lives under a general system of law, than in solitude, where he is independent.