Looking at Aquinas in Latin and English I was struck by the way that a modern translator has consistently rendered 'astrologia' as 'astronomy'. And this reminded me of the challenge of translating technical terms in general. Words representing concepts that are pretty much the same across all human societies - say 'dwelling place' or 'age' or 'clothing' - the problem is not so great, although even here there are difficulties ('bungalow').
For technical terms the difficulties are multiplied. Is the word being used as a technical term, or just figuratively? Take materia. Do you translate it as 'material', which is what the Latin really means? Or do you recognise that it may have taken on a technical meaning at the time of use, in which case 'matter' is probably better? There is a similar problem with continuum. Do you render it literally as 'the continuous', or as the mathematical term 'the continuum'?
In both cases, and particularly the latter, you face the added problem of Latin words that were imported into English (mostly in the fifteenth and sixteenth centuries) because English itself had no corresponding terms for the idea. Nearly all of our philosophical vocabulary, and much of our scientific vocabulary, is taken from Latin. But the technical meaning may have changed considerably since the importation. 'Matter' probably has different connotations now (i.e. as something that has mass) than it did in the medieval period (when mass and weight were not properly distinguished). And 'the continuum' has a special meaning for mathematicians now - in connection with Cantor and uncountability and all that - that it could not have had for medieval writers such as Thomas of Sutton or Ockham.
Terms that have fallen into disuse represent a different problem. 'Quiddity' is simply an English version of the Latin 'quidditas'. Both are invented terms, and represent an utterly outmoded philosophical theory. Thus it means whatever the Latin writers thought it meant. But then you have to explain what they did mean, and that is difficult, because it is not clear to anyone what they did mean, and it probably wasn't clear even to them, either. There are further difficulties with terms that have acquired a common use outside science, or which are of 'general intellectual interest' not specific to any discipline. For example 'per se'. Does the common use reflect the real, original meaning, given that 'per se' and 'quiddity' really live in the same house and form part of the same outmoded theory? Are we, as it were, being eliminativists about quiddity, but reductivists about 'per se'? A priori is another problem that I discussed earlier.
Finally, astrologia. Do we translate it as 'astronomy' or 'astrology'. For 'astronomy', there is the argument that Aquinas was writing about the science of his time, which included the study of heavenly bodies that they called astrologia. The modern equivalent of that is astronomy'. For 'astrology' there is the argument that astrologia, as a theory, was much closer if not identical to what we call 'astrology', as the name suggests. It involved a smaller number of planets, the idea that the earth was the centre of the universe, and the theory that they physics of the sub-lunary sphere was fundamentally different from that of the heavenly bodies, plus many other wrong ideas, including that the heavenly bodies somehow influenced human life and thought. You might argue that Aquinas thought astrologia was a science, whereas 'astrology' is now just a jokey thing you find in the darker parts of the Daily Mail, but the reply to that is that plenty of people still do think that astrology is a science.
This is a question about translation, the only resolution of which is to supply the reader with both the original and the translation in close proximity, which is the purpose of the Logic Museum. But it is connected with a deeper question about the connection between science and philosophy, which I shall explore later.