Ad vivum, naer het leven, from the life: Defining a mode of representation

En route to Vienna in the winter of 1620, the English ambassador Sir Henry Wotton stopped in the city of Linz where he met Johannes Kepler, at that time District Mathematician under Matthias I. In a letter Wotton wrote to Francis Bacon from Vienna in December of the same year, his encounter with Kepler in some detail: In this man's study I was much taken with the draft of a landscape on a piece of paper, methought masterly done: Whereof inquiring the author, he bewrayed with a smile it was himself; adding, he had done it non tanquam pictor, sedtanquam mathematicus [not as a painter, but as a scientist]. This set me on fire. At last he told me now. He hath a little black tent (of which stuff is not much importing which he can suddenly set up where he will in a field, and it is convertible (like a windmill) to all quarters at pleasure … [and is fitted with] a long perspective trunk … through which the visible radiations of all the object without are intromitted, falling upon a paper, which is accommodated to receive them; and so he traceth them with his pen in their natural appearance, turning his little tent round by degrees, till he hath designed the whole aspect of the field. This I have described to your Lordship, because I think there might be good use made of it for chorography: For otherwise, to make landscape by it were illiberal, though surely no painter can do them so precisely.