Benjamin Jowett, letter to Evelyn Abbott (July 24, 1881), in Evelyn Abbott and Lewis Campbell, The Life and Letters of Benjamin Jowett
, Vol. II (London: John Murray, 1897), p. 204:
It is certainly true that we cannot expect to translate fairly one of the world's masterpieces without writing the translation five or six times over. A translation of Demosthenes must be the work of many years, perhaps of ten years. Every sentence has to be studied by itself and in connexion with other sentences.
The first point is clearness; then (2) idiom (which means the use of familiar language); then (3) the avoidance of tautology (the Greek, even Demosthenes, has far more tautology than English); then (4) accuracy, which is clearness in small things, especially in relatives and antecedents, and in giving the right relation to clauses. There are two characteristics of Demosthenes, dignity and rapidity, and it is very hard to combine them.
The slight personification of the Greeks arising out of the genders always strikes me as one of the greatest difficulties in translation. You cannot attribute any living or lifelike action to 'it' or 'its,' and hence a great deal of transposition becomes necessary. Weak constructions must be avoided, e.g. the infinitive after the substantive, unless it has passed into an idiom, which is sufficient to sanction almost any construction. The participle for the substantive should very rarely be used. The sensitiveness of the English language to tautology is really exquisite; it excludes 'to' 'to,' in the same sentence, or the demonstrative 'this' 'this,' which is common enough in Greek.
The true test of translation is not a good phrase as a boy at school supposes, or a good sentence as some Cambridge men imagine (if the particles are duly represented), but an equable and harmonious paragraph, or rather a harmonious whole. English is much simpler than Greek, and therefore the English translation has to be simplified, and complex relations often omitted. Greek is latitudinal (μέν, δέ, &c.) and longitudinal (γάρ, οὖν, &c.). But English is neither. There is much less subordination and much more co-ordination.