The same blessed Spirit who shines as with a ray of light and life into the conscience, to make it feel the guilt of sin, the curse of the law, and its own miserable state as a transgressor, leads it also into this secret, that it has no strength.
Have you never felt that you were utterly powerless—that you would believe, but could not; would hope, but could not; would love, but could not; would keep God's word, but could not; would obey his commandments, but were not able? Has a sense of your own miserable impotency and thorough helplessness never pressed you down almost to despair? You felt sure that there was a faith, a hope, a love, a blessing, and a blessedness in the truth of God; a pardon, a peace, a heavenly joy; an assurance of salvation, a union and communion with the Lord Jesus, which you saw, but could not reach. You felt that if you could believe, all would be well, but believe you could not.
Thus you learnt you had no strength, and as we learn our weakness in this way, we begin to learn also in whom is our strength; and as we get access to Christ by a living faith, we receive strength out of him for a supply of our spiritual necessities.
Despairing of all strength in self, we look to the Lord Jesus Christ, at the right hand of the Father, to give us his; we lift up our prayers and supplications to the great High Priest over the house of God, to strengthen us with strength in our soul; and when he is pleased, in answer to prayer, to send down his Spirit and grace, we are "strengthened with all might, according to his glorious power unto all patience and long-suffering with joyfulness." This is being "strong in the Lord and in the power of his might;" and a being "strengthened with might by his Spirit in the inner man."