Letters 88.33

Wisdom is a large and spacious thing. It needs plenty of free room. One must learn about things divine and human, the past and the future, the ephemeral and the eternal; and one must learn about Time. See how many questions arise concerning time alone: in the first place, whether it is anything in and by itself; in the second place, whether anything exists prior to time and without time; and again, did time begin along with the universe, or, because there was something even before the universe began, did time also exist then?

Seneca, Letters to Lucilius 88.33, translated by Richard Mott Gummere