Fire is one of the ways people disinfect things. Although the “science” of bacteria was unknown at the time of Isaiah, the Israelites had “purification” ceremonies ingrained in the law of Moses. One may wash things which would be destroyed by fire, burn things which are not destroyed by fire (a superior method), but things of little cost, (I assume), which still could harbor visible molds/mildews/etc. (like common earthen clay pots), were to be broken and disposed of.
I suspect there may be other (deeper) logic concerning the reason clay pots were to be broken – than cost – , but I am not aware of them at this time.
When God is shown in vision, the vision is for the “eyes” of the imagination to “see” – not the naked eye of our body.
Since man is made in God’s image and likeness (not identity) which is spoken clearly in the first few pages of Genesis – then it is not surprising that in a “vision” of God one would see the image(s) which best describe him – man and fire.
He is the source of purification and holiness.
There is a difference between seeing a “vision” of me – and actually “seeing” me. One could make a “picaso” image of me – which all would recognize as a symbolic representation of one View of me. Just so, Visions of the father are not actual pictures of him – as “Spirit”, God the father is invisible to the human eye.
Also, to expand on the idea a bit,
Purification (by fire) is a common theme regarding Israel: eg:
Jerim 23:28 The prophet that hath a dream, let him tell a dream; and he that hath my word, let him speak my word faithfully. What is the chaff to the wheat? saith the LORD
Jerim 23:29 Is not my word like as a fire? saith the LORD; and like a hammer that breaketh the rock in pieces?
Fire is not literal here, but an “image” – chaff is necessary for wheat to grow, eg: it is in fact part of the plant – but at the death of the plant, the chaff serves no more purpose. It is waste material, to be burned.
The images take on different forms, as:
Matth 3:11 I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire:
Matth 3:12 Whose fan is in his hand, and he will throughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire.
This passage does not show that purging also means something is kept – eg: the wheat of harvest. But St. Paul clearly shows that purging is a saving action as well:
1Cori 3:11 For other foundation can no man lay than that is laid, which is Jesus Christ.
1Cori 3:12 Now if any man build upon this foundation gold, silver, precious stones, wood, hay, stubble;
1Cori 3:13 Every man’s work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man’s work of what sort it is.
1Cori 3:14 If any man’s work abide which he hath built thereupon, he shall receive a reward.
1Cori 3:15 If any man’s work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire.
The point being that corruptible (dead items) such as hay, (dead) wood, stubble, are flammible – like chaff. They were perhaps necessary in this life – but are not worthy of eternal life. Here, grain is not mentioned – for it would be confusing – the resurrection is after the body (seed) is raised again.
St. Thomas said of his work the Summa – all I have written is chaff – but God said to him, of
me you have spoken well. The essence of God Thomas barely grasped – and if all else he said is chaff, what of it? He still has the foundation and he built the monument to essence and being and act together with God, on the foundation laid by God.
The angel comes to the prophet who recognizes his “uncleanliness” the fire cleanses his lips so that he may speak the words of God – truly, and not in the “dirt” left by past sins.
