91. But unless man's state in which, from being spiritual, he is becoming celestial is known, one cannot possibly perceive what these expressions embody, for they are quite deep arcana. When he is spiritual, the external man is not yet willing to comply with and serve the internal man, and so there is conflict. But when he is becoming celestial, the external man starts to comply with and serve the internal. As a result conflict ceases, and tranquillity ensues; see 87. This tranquillity is meant by 'the rain' and by 'the mist', for it resembles a mist, with which his internal man waters and bathes the external. This serenity which is characteristic of Peace brings forth the things which are called 'the shrub of the field' and 'the plant of the field'. Specifically, these are the rational concepts and the facts that have a celestial-spiritual origin.

Dust, in Ezekiel 26:12, signifies the lowest things which are of the sensual principle of man. They can be either good or bad, depending on the context.

In Isaiah 40:12, the dust signifies exterior or natural truths and goods of heaven and the church.

In Genesis 2:7, the dust is good, and we see some interesting nuances:

First, there's this: 'To form the man, dust from the ground' is to form his external man, which had not previously been man... (Arcana Coelestia 94)

Here, this formation of our external body and mind is a precursor, setting the stage for God to "breathe into our nostrils".

In Arcana Coelestia 1610, we find this passage, where again, dust has a good signification:

'Dust of the earth' has regard to those things that are celestial, for, as shown already, 'the earth' means the celestial aspect of love; 'dust of the sea' has regard to those things that are spiritual, for 'the sea', as has also been shown, means the spiritual aspect of love; while 'as the stars of heaven' means both but in a higher degree. And because these things cannot be numbered they therefore became common expressions to describe growth and multiplication beyond measure.

Then, in Arcana Coelestia 3707, these ideas get pulled together:

The reason the dust of the earth symbolizes goodness is that the earth, [or land,] symbolizes the Lord’s kingdom and therefore goodness, as shown just above in §3705. The dust of that land, then, means goodness, but earthly goodness, since the land symbolizes what is lowest in the Lord’s kingdom....

But there are bad connotations, too. In Micah 7:14-17, licking dust symbolizes being only sensual - bodily and external, worldly, and selfish. It's much the same in Psalms 72:9, where "Barbarians will bow down before God, and His enemies lick the dust...". See Arcana Coelestia 249, 3413 for interesting explanations of this.

(Odkazy: Apocalypse Explained 1145)