A.T. Robertson Commentary Ephesians 3:18

"may be strong to apprehend with all the saints what is the breadth and length and height and depth," — Ephesians 3:18 (ASV)

That ye may be strong (ινα εξισχυσητε). Sub-final clause again with ινα and the first aorist active subjunctive of εξισχυω, a late and rare compound (from εξ, ισχυω) to have full strength. Here only in N.T.

To apprehend (καταλαβεσθα). Second aorist middle infinitive of καταλαμβανω, old and common verb, to lay hold of effectively (κατα-), here with the mind, to grasp (Acts 25:25).

With all the saints (συν πασιν τοις αγιοις). No isolated privilege. Fellowship open to all. Paul gives a rectangular (four dimension) measure of love (breadth πλατος, length μηκος, height υψος, depth βαθος, all common enough words).