To complement to S's recent post on Solomon Dubno, I decided to post this fascinating passage from R' Yaakov Emden's Megillat Sefer which describes the way in which he aquired his vast secular knowledge.
"I yearned to know and to recognize the script of the German language in its own form, which my revered father never taught me, nor did I learn their handwriting from a teacher. It was necessary for me to learn by myself. My heart was always inclined to know (and) to examine worldly matters as well; the (various) nations and faiths, their characteristics and dispositions, their histories and sciences, all of whose matters cannot be known from our sacred books.
This was also (necessary) in order to know how to respond (to a heretic),to mingle comfortably
with people, to know the proper etiquette of each country, the nature of the lands and of their inhabitants, to reveal their secrets and to overcome any difficulties. All this I yearned to learn from their own books in the original. (Yet,) I found no way or manner to achieve this for I did not permit myself to hire a teacher for reading foreign books. I feared a great waste (of time from Torah studies). It was also abominable in my eyes to spend money for this (and), in addition to which, I was simply embarrassed to do so lest people find out.
Behold, I knew (that) a young lad from among the servants was learning to write and read the German language. I clandestinely took him aside and asked him to show me the shape of the printed letters in the foreign alphabet. He had just begun to learn from a Christian teacher who was a scribe and he still barely knew the shape of the separate letters,without knowing how to read the connected letters nor understand the meaning of their words. The lad showed me just once or twice to say this is A, this is B, this is C, etc. Nothing more. With the help of God, may He be blessed, who endows man with wisdom, I immediately grasped the recognition of the letters in their forms. I then struggled by myself alone to put together the words; I applied myself and understood the matter without any assistance from any tutor or teacher whatsoever. Within a short time, I acquired the ability to read a German book as well, as if I had a teacher for this for many years.
However, I succeeded in reading only their printed books and Latin script. But the German
script, with its swift connected flourishes, I still cannot recognize because of my inadequate study. Even in the printed Latin script there remained certain forms and markings or changes in the image of the letters that I do not know to this day.
For this matter I snatched surreptitiously and fleetingly. Even the lad who had shown me was not perfect.Afterwards, I was ashamed to ask anyone (to help me with) that which I failed to understand of their wisdom. With it all, I hastened to read all their printed books immediately by myself until I acquired the skill to read even the Dutch language and gazettes and also to understand much of the Latin language.
I read many of their books with all varied information about Europe, to understand all the views of people around the world in matters of their faiths and religious customs and to reveal their
thoughts about us and our holy faith. I also long, my soul yearns to know and to
understand the arrangement of the terrestrial globe which is determined by the celestial movements as described in their books. Although it is explained in our literature, it is done in a very brief manner. I also wanted to know and to perceive matters of nature; the nature of minerals; the qualities of plants and grasses; especially the science of medicine; the practices of nations and kings, their wars and history; their unique tales and the annals of (their) generations; the original ideas of those who write about the lands, oceans, rivers and deserts and those who describe their condition; the designer's craft, skills, cunning, fraud and deception and foolish stories of fabricated contrivances. All of this my eyes saw in their books. I have expert knowledge of them and their deeds. All their thoughts, their frauds and their good qualities are known and revealed to me so as not to be ignorant of the wisdom
of people the world over.
However, I am careful to read and study them only in a place where it is forbidden to meditate on words of Torah, nowhere else. Indeed, on several occasions, I extracted the sweet from the strong. The honey that I found in them I scooped into my hands to use it in the pursuit of the sacred task (to reveal) various esoteric and sealed matters. Above all, I thus succeeded in knowing how to refute (a heretic) and not to be considered a fool in their eyes. As mentioned above, I studied their books in times of leisure especially those in the fields of medical science and health preservation which is the (very) life of all creation. I studied the science of nature which I felt to be absolutely essential for the survival of the human species."
translated by Rabbi Dr. J. J. Schacter - "R' Jacob Emden: Life and Major Works"
Hat tip: S.