I remembered Tacitus as a grumpy stick-in-the-mud, and, while that’s not necessarily an incorrect characterization, I actually enjoyed re-reading him more than I expected.  Three passages which stood out to me, all from the Agricola:

There is no great difference in language [between the Gauls and the Britons], and there is the same hardihood in challenging danger, the same cowardice in shirking it when it comes close. (62)

Interesting that we encounter Romans with this same stereotype of the Britons in Geoffrey of Monmouth, albeit from the other side. I doubt Monmouth read Tacitus, though I have no idea of the Agricola’s reception in the Middle Ages, but I wonder if some diligent detective work might uncover a line of transmission.

Here’s some of that old Tacitus crabbiness:

And so the population was gradually led into the demoralizing temptations of arcades, baths, and sumptuous banquets.  The unsuspecting Britons spoke of such novelties as ‘civilization’, when in fact they were only a feature of their enslavement.  (73)

But representations of the human face, like that face itself, are subject to decay and dissolution, whereas the essence of man’s mind is something everlasting, which you cannot preserve or express in material wrought by another’s skill, but only in your own character.  All that we loved and admired in Agricola abides and shall abide in the hearts of men through the endless procession of the ages; for his achievements are of great renown.  With many it will be as with men who had no name or fame: they will be buried in oblivion.  But Agricola’s story is set on record for posterity, and he will live. (99)