Sources refer to the Ramchal’s Derech Hashem.
Creation is made up of two components, the physical and the spiritual. The physical component is that which we can perceive through our senses. This includes both terrestrial and celestial phenomena. The former includes such things as soil, water and air, while the latter includes the stars and planets.
The spiritual component cannot be detected with our senses, nor through technology. Just as physical things can be categorized as terrestrial or celestial, spiritual things also come in two types: neshamos (souls) and nivdalim (“those set apart”). Souls are spiritual creations designed to be placed into bodies in order to perform certain tasks. Nivdalim, on the other hand, are independent spiritual creations, not designed to merge with bodies. These include both angels and various forces.
There are a number of levels of nivdalim, each with its own distinct nature. Because of this, there are many different types of angels (chayos, serafim, ofanim, etc.).
In all of creation, only man represents a synthesis of the physical and spiritual components, possessing both a body and a higher soul (neshama). Animals do have a type of soul that animates them, but this nefesh is not a spiritual entity. Man’s neshama is an entity entirely independent of his body. [I, 5.1]
Humans are familiar with the physical realm because we live in it. Spiritual matters, on the other hand, are simply outside of our experience, with the result that we lack the capacity to discuss them properly. The only meaningful way we can express ideas on this subject is through the traditions that have been passed down to us.
One of the basic concepts we have received is that everything physical has a spiritual counterpart. The physical and spiritual entities are somehow connected so that the physical item is like an extension of the spiritual thing into our world, like the branch of a tree. Additionally, every physical thing is under the supervision of an “angel” (which need not be a sentient being) whose job it is to maintain the object according to its nature. [I, 5.2]
The physical world’s existence is maintained by these spiritual forces; everything that exists is the result of these forces’ interactions. [I, 5.3] Anything that happens in the physical plane can be attributed to these forces with one exception: God decreed that man should have free will to choose between good and evil. In this, man exists independent of any influence from the spiritual plane. The world is therefore influenced from two directions: downward from spiritual forces and upward from man’s free will.
Since man is a physical being, when he acts on decisions of his free will, he can only affect the physical plane directly. However, since the physical and spiritual worlds are linked, man’s actions indirectly affect objects’ counterparts in the spiritual realm as well.
(It should be noted that, while most of man’s actions are the result of his own free will, some are mandated by God in order to reward or punish a person. This will be covered later, in section 2.8.) [I, 5.4]
God decreed that humans should be able to influence the spiritual realm not only through his actions but also through his words and even through his thoughts. God has, however, set limits to the amount that humanity can affect the spiritual world. [I, 5.5] Since the two realms are linked, when a person affects the spiritual realm, it has repercussions in the material world. [I, 5.6]
We have already discussed (in sections 2.2 and 2.3), that God has decreed that both good and evil exist in this world. That being the case, it necessarily follows that these things have corresponding forces in the spiritual realm, from which they emanate. A state of goodness occurs when a force has the potential to be enlightened by God’s Presence; a state of evil occurs when this potential does not exist and God’s Presence is concealed. [I, 5.7]
All goodness is the result of God’s Presence and all evil is the result of the absence of same. Therefore, God is the direct cause of goodness but, since it is only His Presence being withheld that results in evil, He cannot be said to be the cause of it. As the Sages tell us, God does not associate His Name with evil (Bereishis Rabbah 3:6).
The degree of influence that spiritual forces of evil are able to exert all depends on the degree to which God’s Presence is revealed or concealed. When evil forces are strengthened, the corresponding forces of good become weakened, but when the forces of evil are weakened, those of goodness are strengthened. When a force of good or evil gains power, its influence on spiritual and physical things increases. When a force is weakened, its influence decreases. [I, 5.8]
These evil forces come in a variety of degrees, known by such names as impurity, darkness, pollution, mundanity, etc. (In Hebrew, tumah, choshech, zuhama, and chol, respectively.) The forces that result from God’s Presence being revealed are known by names like holiness, purity, light and blessing (kedusha, taharah, ohr and bracha, respectively). Each one of these forces – both good and evil – has spiritual beings (“angels”) appointed to convert the force into results in the physical world. God has created the universe so that His will is carried out through such “angels,” each one responsible for its own assigned sphere of influence. [I, 5.9]