From the book "Jap Ji – The message of Guru Nanak", written by Sant Kirpal Singh

Guru Nanak says that creation is divided into three main grand divisions.

The first is the 'Region of Truth and Pure Spirit' unmixed with matter.
Ramkali M. 5

Here the spirit reigns supreme and there is total absence of matter. This is the region where the Lord Himself dwells and may be defined as the purely spiritual region. This is free from the haunt of death and destruction. Whoever reaches its domain, obtains true salvation. The Master says:

Once you reach the region of the Formless,
you obtain the abode of everlasting joy and peace.

Sorath M. I

The Formless dwells in the Pure Spiritual Region.

Jap Ji Stanza 37

The second grand division consists of Pure Spirit and a subtle form of matter combined in varying degrees. The upper part of it is called Par Brahmand, wherein the spirit is more to be compared with the subtle forms of matter. In the lower parts called Dasam Dwar, both are in equal part. This is the region of the universal mind and is termed by various names by various Masters. Here the spirit is mixed with matter in its subtlest form, the latter being totally subordinate to the former. Spirit in this region predominates and is pre­eminently the ruling force. This region undergoes a change at the destruction of the universe in the grand dissolution (Maha Pralaya), and in dissolution (Pralaya). A man in this domain is safer than in the one below it.

The third region is the grand division of spirit and matter in its grossest form and is called And. It is comprised of Trikuti and Sahansrar planes. It is the sphere of Maya or matter. In this region matter has the upper hand and spirit is subordinate to it, so much so, that the latter feels dependent on the former for its manifestation. In this region the spirit, on account of its association with matter, undergoes untold miseries and is subjected to the law of transmigration. Both these divisions are referred to as Kaal and Maha Kaal respectively.

In going upward, after rising above the body-consciousness, we first find ourselves hemmed in by matter all around in the And (the third grand division). Then we have to rise into the Brahmand, the region of the universal mind. There we feel much better, but still we are not immune from danger or destruction. The first region or haven of safety is the Sach Khand, or the Realm of Truth, which is above the reach of Maha Kaal or the grand dissolution. This, in brief, is a sketch of the macrocosm – the Great World Universe. These three divisions also exist in man on a miniature scale. If you want to know about macrocosm, you must first know about the microcosm. Guru Nanak says:

In the body itself there is everything: the spiritual region,
the heavenly plateaux and the material planes.
In the body dwells the Lord Supreme who nourishes all.
In the body lives the Formless, the Inconceivable,
beyond the human ken.
Those who have material eyes only,
seek Him in vain, in outward things.

In the body there are the priceless jewels of Divinity.
In the body there are all the material realms and planes.
In the body is the treasure of the Holy Naam,
reached only through meditation on the Word of the Master.
In the body are all the gods: the Brahma,
the Vishnu and the Shiva, and the whole creation itself.

Rag Suhi M. 3

Another Saint also has said the same thing:
Brahmand is in man on a miniature scale,
and whoever seeks it, will find it.
O Pipa, the highest Truth may be realized only through a Master.
Dhanasri Pipa

This very truth is also enunciated by the Muslim Saints who state:
Macrocosm is in the microcosm and thus you get to God.

In the human body, we trace the three divisions referred to above on a miniature scale.