Although, as a concrete image answering to some definite succession of experiences a year is a gross misrepresentation, as a general concept implying a collection of a certain number of similar successions of experience it is sufficiently exact.

That is to say, though we cannot imagine the _absolute_ duration of any such cycle of experience, we can, by the simple device of conceiving certain durations as multiples of others, perfectly well compare different periods of times, and so appreciate their _relative_ magnitudes.
Leaving, then, this constant error in time-appreciation, we will pass to the variable and more palpable errors in the retrospective measurement of time.

Each person's experience will have told him that in estimating the distance of a past event by a mere retrospective sense of duration, he is liable to extraordinary fluctuations of judgment.

Sometimes when the clock strikes we are surprised at the rapidity of the hour.

At other times the timepiece seems rather to have lagged behind its usual pace.
And what is true of a short interval is still more true of longer intervals, as months and years.