Here the Prophet says, that the Israelites did secretly, and by hidden means, prepare their hearts for deeds of evil; and he takes up nearly the same similitude as he did a little while before, though for a different purpose; for he says that they had prepared their hearts secretly, as the baker puts fire in the night in his oven, and then rests, and in the morning the oven is well heated, having attained heat sufficient to bake the bread. The oven becomes hot in the morning, though the baker sleeps. How so? Because an abundance of fuel had been put together, so that it is heated by the morning. Hence nocturnal rest does not prevent the fire from making hot the oven, when it has a sufficient quantity of fuel, when the baker has so filled his oven, that the fire cannot be extinguished, nor be gradually smothered. When the baker has thus set in order an heap of wood, he then securely rests, for the fire can continue until the morning. We now then see the design of the Prophet.

They have prepared, he says, their hearts insidiously; that is, though they have not at first made evident their wickedness, they have yet previously prepared their hearts, as the oven is lighted up, or as the furnace is heated before the bread is prepared; nay, there is no need of much bustle, -- there is no need of much noise when the baker lights up his oven, for he prepares the wood, and then he goes to rest; and, in the meantime, while he sleeps all the night, the fire is burning. So also they, though all do not perceive their wickedness, they have yet, in the meantime, heated their hearts like an oven; that is, evil deeds have, by degrees and during a long period of time, been conceived by them, before they came forth into open acts of wickedness.

We hence see that the similitude of an oven is set forth here by the Prophet in a sense different from what it had been before; and this ought to be noticed, because interpreters heedlessly pass over this wholly, as if the Prophet meant in both places the same thing. But the meaning, as it is evident, is far different. For he intended only, in the first instance, to reprove the mad lust with which they were burning; but he now speaks of their plots and concealed frauds; that is, that the Israelites before openly showed themselves to be ungodly and wicked, but that they were now wicked before God. How so? Because they were now like an oven lighted up in the night; for as the baker, having closed the door of his house, puts in fire, while none perceive that the furnace or the oven is being heated; so also the people fed and nourished their wickedness before God; and afterwards, in course of time, it broke forth openly, whenever an opportunity was offered.