Reading Sōseki Natsume's Ten Nights' Dreams brought back many old questions about how translation is supposed to work. The opening line to each chapter is the same, and while the original Japanese text is unambiguous —
— you could render this any number of ways in English:
I had this dream
I dreamed this
Thus I dreamed
I saw this in a dream
I saw this dream
I had a dream that went like this
I once had a dream
...and so on. Tashima / Lorentz (the translators for my edition) put it as "This is the dream I dreamed", which is a little wordy for my taste. My own preferred reading is I had a dream [like this] or I once had this dream, which doesn't introduce a sonorous repetition that wasn't in the original to begin with and also isn't so short that it comes down with a bump. Thus I dreamed sounds appropriately ponderous and, well, even a bit dreamy, but maybe a bit too much.
Not long ago I took a crack at translating one of Lorca's poems into English, not least of all because his original Spanish texts are out of copyright and because the English translation I found was not.
Se ha llenado de luces mi corazón de seda, de campanas perdidas, de lirios y de abejas. Y yo me iré muy lejos, más allá de esas sierras, más allá de los mares, cerca de las estrellas, para pedirle a Cristo Señor que me devuelva mi alma antigua de niño, madura de leyendas, con el gorro de plumas y el sable de madera.
My silken heart, it’s filled with light; with long-lost bells, with lilies and bees. I’ll go so very far, past all those hills, past all the seas, near to the stars and beg of Christ the Lord give back the soul I once had when I was a child, ripe with legends, with a plumed cap and a wooden sword.
For my favorite example for how much you can cram into or get out of a few words, see Douglas Hofstader's Le Ton Beau De Marot: In Praise Of The Music Of Language, in which he attempts to translate a virtually untranslable French poem (simply because it's so compact and sparse) and in the process opens up a whole little universe of convolutions.