Following his discussion of the folly of ignorance, William Gurnall posed the question, “But how may an ignorant soul attain to knowledge?” and offered a five-fold answer:

1. “Be deeply affected with thy ignorance.” That is, be humble and teachable.
2. “Be faithful with that little knowledge thou hast.” Be diligent and obedient according to whatever knowledge you do possess.
3. “Ply the throne of grace.” See James 1:5.
4. “Thou must bestow some time for thy diligent search after truth.” Dig! “. . . this treasure of knowledge calls for spade and mattock.”
5. “If thou wouldst attain to divine knowledge, wait on the ministry of the word.” Attend to the teaching of the Word. Be a “wakeful hearer,” an “attentive hearer,” and a “retentive hearer.”

Concerning the last, Gurnall wrote,

Thou must be a retentive hearer. Without this the work will ever be to begin again. Truths to a forgetful hearer are as a seal set on water, the impression lasts no longer than the seal is on; the sermon once done, and all is undone. Be therefore very careful to fasten what thou hearest on thy memory, which that thou mayest do,
   (1.) Receive the truth in the love of it. An affectionate hearer will not be a forgetful hearer. Love helps the memory. ‘Can a woman forget a child, or a maid her ornaments, or a bride her attire?’ No, they love them too well. Were the truths of God thus precious to thee, thou wouldst with David think of them day and night. Even when the Christian, through weakness of memory, cannot remember the very words he hears, to repeat them, yet then he keeps the power and savour of them in his spirit. As when sugar is dissolved in wine, you cannot see it, but you may taste it; when meat is eaten and digested it is not to be found as it was received, but the man is cheered and strengthened by it, more able to walk and work than before, by which you may know it is not lost; so you may taste the truths the Christian heard in his spirit [and] see them in his life. Perhaps if you ask him what the particulars were the minister had about faith, mortification, repentance, and the like, he cannot tell you; yet this you may find, his heart is more broken for sin, more enabled to rely on the promises, and now weaned from the world. As that good woman answered one, that coming from sermon, asked her what she remembered of the sermon; [she] said she could not recall much, but she heard that which should make her reform some things as soon as she came home.
   (2.) Meditate on what thou hearest. By this David got more wisdom than his teachers. Observe what truth, what Scripture is cleared to thee in the sermon more than before, take some time in secret to converse with it, and make it thereby familiar to thy understanding. Meditation to the sermon in what the harrow is to the seed, it covers those truths, which else might have been picked or washed away. I am afraid there are many proofs turned down at a sermon, that are hardly turned up, and looked on any more, when the sermon is done; and if so, you make others believe you are greater traders for your souls, than you are indeed. It is as if one should come to a shop and lay by a great deal of rich ware, and when he hath done goes away, and never calls for it. O take heed of such doings. The hypocrite cheats himself worst at last.
   (3.) Discharge thy memory of what is sinful. We wipe our tablebook and deface what is there scribbled, before they can write anew. There is such a contrariety betwixt the truths of God, and all that is frothy and sinful, that one puts out the other. If you would retain the one, you must let the other go.

—William Gurnall, The Christian in Complete Armour (Banner of Truth Trust, 2002), 1:176–177.