'The former heavens, which passed away,' as mentioned in Revelation 21:1, signify the societies of people in the spiritual world who were only in external or apparent good. (Apocalypse Explained 675) Heavens are celestial and spiritual things. Consequently, they are inmost things, both of the Lord's kingdom in heaven and in the earth. This also refers to the church, and every individual, who is a kingdom of the Lord, or a 'church.' Consequently, heavens denote all things pertaining to love and charity, and faith grounded in them, as well as all things pertaining to internal worship. In like manner they denote all things pertaining to the internal sense of the Word. All these things are heavens, and are called, 'the throne of the Lord.' (Arcana Coelestia 2162)

(References: Apocalypse Explained 21)

978. What the internal man is and what the external, few if any know nowadays. They imagine that these are one and the same, the chief reason being their belief that they do what is good and think what is true from their proprium; for the proprium carries such belief within itself. But the internal man is as different from the external as heaven from earth. When the learned as well as the unlearned reflect on the matter, they have no other concept of the internal man than of thought, seeing that it is something inward; and no other concept of the external man than of the body and its ability to perceive with the senses and to experience pleasure, seeing that it is something outward. But thought, which they imagine to belong to the internal man, does not in fact belong to the internal; for with the internal man resides nothing but goods and truths which are the Lord's, and in the interior man conscience has been implanted by the Lord. Even the evil, indeed the most evil, possess thought, and people who are devoid of conscience have it too. From this it is clear that man's thought belongs not to the internal man but to the external. And the fact that the body, and its ability to perceive with the senses and to experience pleasure, is not the external man is clear from the consideration that spirits likewise, who do not possess the [physical] body such as they had while living in the world, still have an external man.

[2] But what the internal man is and what the external nobody can possibly know unless he knows that in everyone there is a celestial and spiritual degree corresponding to the angelic heaven, a rational degree corresponding to the heaven of angelic spirits, and the interior sensory degree corresponding to the heaven of spirits. There are indeed three heavens, the same number as there are degrees with man. These heavens are quite distinct and separate from one another, which is why after death the person who has conscience is first of all in the heaven of spirits; after that he is raised by the Lord into the heaven of angelic spirits, and finally into the angelic heaven. This could not possibly take place if there were not the same number of heavens to which, and to the state of which, he is capable of corresponding. This has made clear to me what constitutes the internal man and what the external. Celestial and spiritual things form the internal man, rational things the inner or middle, and sensory things - not those of the body but those derived from bodily things - the external. And this applies not only to man but also to a spirit.

[3] Let me speak in terms used by the learned. These three are like end, cause, and effect. It is well known that no effect can possibly exist unless there is a cause, nor any cause unless there is an end. Effect, cause, and end are as distinct and separate from one another as exterior, interior, and inmost are. Strictly speaking the sensory man, that is, the one whose thought is based on sensory evidence, is the external man, while the spiritual and celestial man strictly speaking is the internal man. But the rational man comes in the middle between the two, and by way of this man - the rational - communication takes place between the internal man and the external. I know that few can grasp these ideas, the reason being that they live among, and think from, external things. This is why some equate themselves with animals and believe that when their bodies die they will be altogether dead. Yet it is when they die that they first start to live. In the next life people who are good lead first a sensory life in the world or heaven of spirits, then a more interior sensory life in the heaven of angelic spirits, and finally an inmostly sensory life in the angelic heaven. This latter or angelic life is the life of the internal man, about which hardly anything can be said that man is capable of grasping.

[4] The regenerate can know of the existence of that internal life only if they reflect on the nature of good and truth and of conflict. Actually that life is the Lord's life with man, for the Lord by way of the internal man works the good of charity and the truth of faith within the external man. That which from this is perceived in his thought and affection is something general, containing countless details which come from the internal man but which a person does not perceive at all before entering the angelic heaven. Concerning the nature of this general something, see what has been told from experience in 545. These matters that have been stated concerning the internal man however, since they lie beyond the grasp of most people, are not vital for their salvation provided they know of the existence of the internal man and of the external, and acknowledge and believe that everything good and true comes from the Lord.