Charles H. Spurgeon on Psalms 77:10

Infirmity. An infirmity is this, —some sickness or indisposition of the soul, that arises from the weakness of grace. Or an infirmity is this, —when the purpose and inclination of the heart is upright, but a man wants strength to perform that purpose; when "the spirit is willing, but the flesh is weak" (Mt 26:41); when a man can say with the apostle, "To will is present with me; but how to perform that which is good I find not, "Ro 7:18. When the bent and inclination of the soul is right, but either through some violence of corruption or strength of temptation, a man is diverted and turned out of the way. As the needle in the seaman's compass, you know if it be right it will stand always northwards, the bent of it will be toward the North Pole, but being jogged and troubled, it may sometimes be put out of frame and order, yet the bent and inclination of it is still northward; this is an infirmity. James Nalton. 1664.