They (the Athenians) are innovative and sharp in their thinking and very capable in carrying out what they decide, while you are content with maintaining what you have acquired and do not invent anything and do not even carry out the necessary things.
On the other hand, they venture without measuring their strength, they take risks without being stopped by the suggestions of logic and in the midst of difficulties they maintain hope. While you do less than you can and mistrust those whom you judge of course and believe that you will never be freed from your troubles. And they are indefatigable, while you are hesitant, and they are easily lost, while you are rooted in your place, because they believe that by their absence they will gain something, while you how by leaving you will endanger what you have, And when they defeat their enemies they take advantage of victory as much as possible, and rarely retreat when defeated. (... ) And if they do not manage to implement what they have devised, they consider that they have been deprived of something that already belonged to them, but what they acquire through their activity, they consider little, in relation to what they expect to achieve, and, if again try something and fail, they immediately make up for it with new hopes. Because, only for them, having something and waiting to get what they put in their mind are one and the same, because they quickly try to implement what they think. And for all this they toil with sufferings and dangers all their lives and rejoice little in what they have, since they are always acquiring more, not thinking of a celebration other than the performance of their duties, because they consider the quietness of idleness a greater calamity than laborious occupation. If someone were to say about them that their nature is to neither have peace themselves nor leave others in peace, they would be telling the truth.
By the mouth of the Corinthians sent to Sparta
Thucydides, I, 70, 2-9