Commentaries:
Robertson's Word Pictures (NT)
If thou canst (to ei dunh). The Greek has a neat idiom not preserved in the English translation. The article takes up the very words of the man and puts the clause in the accusative case of general reference. "As to the 'if thou canst,' all things can (dunata) to the one who believes." The word for "possible" is dunata, the same root as dunh (canst). This quick turn challenges the father's faith. On this use of the Greek article see Robertson, Grammar, p. 766.
Other Robertson's Word Pictures (NT) entries containing Mark 9:23:
Mark 9:14
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