{The Son} (ho huios). The absolute use of the Son in
relation to the Father admitting the charge in verse  18  and
defending his equality with the Father. {Can do nothing by
himself} (ou dunatai poiein aph'heautou ouden). True in a sense
of every man, but in a much deeper sense of Christ because of the
intimate relation between him and the Father. See this same point
in  5:30  7:28  8:28  14:10 . Jesus had already made it in
 5:17 . Now he repeats and defends it. {But what he seeth the
Father doing} (an m(8820)ti blep(8869) ton patera poiounta). Rather,
"unless he sees the Father doing something." Negative condition
(an m(885c)=ean m(885c), if not, unless) of third class with present
(habit) subjunctive (lep(8869)) and present active participle
(poiounta). It is a supreme example of a son copying the spirit
and work of a father. In his work on earth the Son sees
continually what the Father is doing. In healing this poor man he
was doing what the Father wishes him to do. {For what things
soever he doeth, these the Son also doeth in like manner} (ha
gar an ekeinos poi(8869) tauta kai ho huios homoi(9373) poiei).
Indefinite relative clause with an and the present active
subjunctive (poi(8869)). Note ekeinos, emphatic demonstrative,
that one, referring to the Father. This sublime claim on the part
of Jesus will exasperate his enemies still more.