The Lord Jesus had no need to bear the cross, endure trials, except to attest and prove his obedience towards God his Father. But necessary for us it is, for several reasons, to be unceasingly afflicted in this life. First, as we are by nature inclined to exalt ourselves and claim all things for ourselves, if our frailty is not set before our very eyes, we immediately value our own virtue beyond measure, unhesitatingly deeming itself unconquerable against all troubles that could beset it.
From this it comes to pass that we are puffed up in empty foolish confidence in the flesh, which later rouses us to haughtiness against God as if our own strength suffice without his grace. This arrogance he best restrains in showing us by experience how in us there lies not only stupidity–but also frailty. Therefore he afflicts us either by disgrace, by poverty, disease, bereavement, or other calamities to which—resist them as we will–directly we succumb, not having the power to bear them.
Thus humbled, we learn to call upon his power, which alone makes us stand firm, unflinching, under the weight of such burdens.
—-”The Piety of John Calvin” pp. 88