Understanding

In 2 Nephi 31:3 we read

For the Lord God giveth light unto the understanding

How? The answer is found in several other Book of Mormon passages.
1 Nephi 15:7-10

Behold, we cannot understand the words which our father hath spoken…And I said unto them: Have ye inquired of the Lord? And they said unto me: We have not; for the Lord maketh no such thing known unto us. Behold, I said unto them… How is it that ye will perish, because of the hardness of your hearts

2 Nephi 32:4

now after I have spoken these words, if ye cannot understand them it will be because ye ask not

Mosiah 13:32

they did not all understand the law; and this because of the hardness of their hearts

Mosiah 26:3

because of their unbelief they could not understand the word of God; and their hearts were hardened.

Alma 33:20

But few understood the meaning of those things, and this because of the hardness of their hearts.

Mosiah 12:27

Ye have not applied your hearts to understanding; therefore, ye have not been wise.

Mosiah 3:15

they hardened their hearts, and understood not

3 Nephi 19:33

their hearts were open and they did understand

Mosiah 2:9

open your ears that ye may hear, and your hearts that ye may understand

Alma 32:28

Now, we will compare the word unto a seed. Now, if ye give place, that a seed may be planted in your heart, behold, if it be a true seed, or a good seed…ye will begin to say within yourselves… it beginneth to enlighten my understanding