As a child I enjoyed doing cryptogram puzzles.
Here's an interesting excerpt from Solomon Maimon's (1754-1800) autobiography1:
I possessed some disconnected knowledge in history, astronomy, and other mathematical sciences. I burned with desire to acquire more knowledge, but how was this to be accomplished in the want of guidance, of scientific books, and of all other means for the purpose ? I was obliged therefore to content myself with making use of any help that I could by chance obtain, without plan or method.
In order to gratify my desire of scientific knowledge, there were no means available but that of learning foreign languages. But how was I to begin ? To learn Polish or Latin with a Catholic teacher was for me impossible, on the one hand because the prejudices of my own people prohibited to me all languages but Hebrew, and all sciences but the Talmud and the vast array of its commentators, on the other hand because the prejudices of Catholics would not allow them to give instruction in those matters to a Jew. Moreover I was in very low temporal circumstances. I was obliged to support a whole family by teaching, by correcting proofs of the Holy Scriptures, and by other work of a similar kind. For a long time therefore I had to sigh in vain for the satisfaction of my natural inclination.
At last a fortunate accident came to my help. I observed in some stout Hebrew volumes, that they contained several alphabets, and that the number of their sheets was indicated not merely by Hebrew letters, but that for this purpose the characters of a second and a third alphabet had also been employed, these being commonly Latin and German letters. Now, I had not the slightest idea of printing. I generally imagined that books were printed like linen, and that each page was an impression from a separate form. I presumed however that the characters, which stood in similar places, must represent one and the same letter, and as I had already heard something of the order of the alphabet in these languages, I supposed that, for example, a, standing in the same place as aleph, must likewise be an aleph in sound. In this way I gradually learnt the Latin and German characters.
By a kind of deciphering I began to combine various German letters into words ; but as the characters used along with the Hebrew letters might be something quite different from these, I remained always doubtful whether the whole of my labour in this operation would not be in vain, till fortunately some leaves of an old German book fell into my hand. I began to read. How great were my joy and surprise, when I saw from the connection, that the words completely corresponded with those which I had learned. 'Tis true, in my Jewish language many of the words were unintelligible ; but from the connection I was still able, with the omission of these words, to comprehend the whole pretty well.
1 "Solomon Maimon: an Autobiography: Tr. from the German with Additions and Notes," translated by John Clark Murray, 1888, pp.89-91.
If you don't have time or interest in reading the entire autobiography, you can read what is essentially an 18-page synopsis (with interesting commentary) here, in an essay from 1895.