An unveiling is an uncovering of what was always present but hidden, the anointed awareness within lifting its own veil so consciousness can see itself at last. It is signified, given in signs and images rather than plain speech, because the deep things of the body and the mind travel in symbol. John is the receiving mind, the faculty that takes down the vision and holds it. What must shortly come to pass is not a distant calendar of nations but the near, ripening change inside the one who is ready.
The whole account is a message the higher self sends downward into ordinary awareness, wrapped in figures so it survives the passage. It comes soon because it is already stirring in the person who can read it.
An angel: a messenger power of the higher mind that carries meaning down into ordinary awareness
John: the receiving faculty in a person that takes in the vision and holds it