according to what His Wisdom and Will necessitated.

Had the Visual Form not existed

Which we behold like all other creatures, But it [the Form] confirms the matter, As an act of Justice, by His Will.

He does what He wills

and to Him belongs the Volition (al-Mashi'u).

Meaning: Had we not beheld and witnessed the Visual Form, we would have been [lost] like the rest of the creatures [who are in ignorance].

Or the meaning is: Had we not beheld it just as the rest of creation beholds it, our Affirmation (Ithbat) of His existence would not have been valid. However, the Glorified One dealt justly with the People of Earth just as He dealt justly with the People of Heaven.

He appeared through it as an intimacy (Ansan) for the people of gnosis,

And distinguished them therein with a Name and an Attribute.

The pronoun in 'through it' refers to the Visual Form. He means: He manifested to them, through them, with a Name and an Attribute, due to their need for Names—that they might call upon Him by them—and for Attributes—that they might infer His existence from them.