These are quotes taken from Thomas Boston’s, Human Nature In Its Fourfold State. The excerpt in full is found on the Providence Baptist Ministries website as provided by Monergism.com.

A man may bring as many buckets of water to a house that is on fire, as he is able to carry, and yet it may be consumed, and will be so, if he bring not as many as will quench the fire. Even so, although you should do what you are able, in keeping the commandments, if you fail in the least degree of obedience which the law enjoins, you are certainly ruined forever, unless you take hold of Christ, renouncing all your righteousness as filthy rags.

Objection 1: If we be under an utter inability to do any good, how can God require us to do it? Answer: God making man upright (Eccl. 7:29), gave him a power to do everything that He should require of him; this power man lost by his own fault…Now, we having, by our own fault, disabled ourselves, shall God lose His right of requiring our task, because we have thrown away the strength He gave us whereby to perform it? Has the creditor no right to require payment of his money because the debtor had squandered it away, and is not able to pay him?

But all this is needless, seeing we are utterly unable to help ourselves out of the state of sin and wrath. Answer: Give not place to that delusion, which puts asunder what God has joined, namely, the use of means and a sense of our own impotency. If ever the Spirit of God graciously influence your souls, you will become thoroughly sensible of your absolute inability, and yet enter upon a vigorous use of means. You will do for yourselves, as if you were to do all, and yet overlook all you do, as if you had done nothing. Will you do nothing for yourselves because you cannot do all? Lay down no such impious conclusion against your own souls. Do what you can; and, it may be, while you are doing what you can for yourselves, God will do for you what you cannot.