John Wesley on Exodus 27:4

The grate was set into the hollow of the altar, about the middle of it, in which the fire was kept, and the sacrifice burnt; it was made of net - work like a sieve, and hung hollow, that the fire might burn the better, and that the ashes might fall through. Now, this brazen altar was a type of Christ dying to make atonement for our sins. Christ sanctified himself for his church as their altar, John 17:19, and by his mediation sanctifies the daily services of his people. To the horns of this altar poor sinners fly for refuge, and are safe in virtue of the sacrifice there offered.