9726. 'And you shall make for it a grating, a network' means the level of sensory perception, which is the last and lowest. This is clear from the meaning of 'a grating, a network' as external sensory perception, thus that which forms for a person the last and lowest level of life; and since this lowest level is meant by the grating it was placed all the way round the altar. Such sensory perception was represented by the grating because it first sifts so to speak and sorts out those things which enter the human mind and present themselves to the understanding and will, namely truths and forms of good. If the sensory perception is composed of good it does not let anything through other than forms of good, and truths derived from good, and rejects evils and the falsities arising from evil. For sensory perception is the actual ability to perceive things which belong to the understanding and to sense those which belong to the will as they exist on outermost levels, an ability that is perfectly fashioned for the affections for those things. The nature of all this may be illustrated by very many things in the body. Everywhere in the outermost parts within the body there are forms that resemble nets and there are so to speak gratings which sort out the things that flow towards them from the world. Those that are suitable are let through because they are desirable, and those that are unsuitable are rejected because they are loathsome. Extremely sensitive systems such as these exist in the stomach. These let through into the blood the suitable juices of the chyle, because these juices are useful and therefore desirable, and reject the unsuitable because they are harmful and therefore loathsome. The situation is similar with sensory perception, which is the last and lowest level of a person's life. But this level with a person has become totally wrecked, the reason why being that it stands right next to and is exposed to the world and is therefore the last to be regenerated, indeed scarcely anyone at the present day is able to be regenerated down to that level. As regards what the level of sensory perception is like with these people, see what has been shown already concerning it in 4009, 5077, 5081, 5084, 5094, 5125, 5128, 5580, 5767, 5774, 6183, 6201, 6310-6318, 6564, 6598, 6612, 6614, 6622, 6624, 6844, 6845, 6948, 6949, 7442, 7645, 7693, 9212, 9216.

Therefore if a person is to see and have an understanding of the truths of faith and the forms of the good of love he must be raised by the Lord above that level to more internal levels. But the sensory perception meant by 'the grating, the network' around the altar is the sensory perception belonging to the Lord's Divine Human, since the altar is representative of the Lord and of the worship of Him that springs from the good of love, 9714.

7645. 'And one will not be able to see the land' means a darkening of the whole natural mind as a result. This is clear from the meaning of 'not being able to see as a darkening, that is, the failure to perceive truth; and from the meaning of 'the land of Egypt' as the natural mind, as above in 7644. But a brief statement must be made to explain why, when the outermost contents of the natural are laid waste, the whole natural mind is darkened as a result. The interior parts of a person's mind reach down into and are based on its lowest and outermost levels, where all its consecutive parts reside together. When there is nothing on the lowest levels but falsity and evil, truths and forms of good flowing from the interior parts into those lowest levels are flowing into evils and falsities there, as a consequence of which they are themselves turned into evils and falsities there. Therefore nothing but falsity and evil is apparent in the whole of the natural. This is what a darkening of the whole natural mind as a result, meant by 'not being able to see the land', describes. Here also is the reason why, when they have undergone vastation, hellish spirits are limited to the outermost parts of the natural. The inferior light they have, which is called the light of understanding, is not unlike the inferior light of this world, which in the next life becomes utterly thick darkness at the presence of the superior light of heaven. Since the outermost part of the natural, called the level of the senses, is filled with illusions and resulting falsities, and with self-indulgence and resulting evils, 6844, 6845, and since the hells are lit by that inferior light, the Lord provides a person when he is being regenerated with the ability to be raised above that level of the senses to more internal levels, see 6187, 6317, 7442.