John Calvin Commentary Luke 10:17

"And the seventy returned with joy, saying, Lord, even the demons are subject unto us in thy name." — Luke 10:17 (ASV)

And the seventy returned. It is evident, that the faith of the seventy disciples in the words of Christ had not been full and complete when they returned, exulting that they had cast out devils by the power of Christ, which they regarded as something new and unexpected. Nay, they had received this power accompanied by a command. At the same time, I have no doubt that, when they departed, they were convinced that nothing that the Master had said to them would fail of its accomplishment; but afterwards, when the matter proceeded to an extent that surpassed their expectations, they were astonished at the sight.⁵¹

And this is frequently the case with believers, that they receive from the word only a slight perception of the Divine power, and are afterwards excited to admiration by actual experience. What was the nature of that joy will more clearly appear from Christ’s reply.

⁵¹ “Ils furent esmerveillez et esbahis de voir cela advenir;” — “they were astonished and overwhelmed at seeing that happen.”;” — “they were astonished and overwhelmed at seeing that happen.”