4 The things then which are seen shall pass away, and there shall come the things which are looked for, things fairer than the present; but as to the time let no one be curious. For it is not for you, He says, to know times or seasons, which the Father has put in His own power. And venture not thou to declare when these things shall be, nor on the other hand supinely slumber. For he says, Watch, for in such an hour as you expect not the Son of Man comes. But since it was needful for us to know the signs of the end, and since we are looking for Christ, therefore, that we may not die deceived and be led astray by that false Antichrist, the Apostles, moved by the divine will, address themselves by a providential arrangement to the True Teacher, and say, Tell us, when shall these things be, and what shall be the sign of Your coming, and of the end of the world?
We look for You to come again, but Satan transforms himself into an Angel of light; put us therefore on our guard, that we may not worship another instead of You. And He, opening His divine and blessed mouth, says, Take heed that no man mislead you. Do you also, my hearers, as seeing Him now with the eyes of your mind, hear Him saying the same things to you; Take heed that no man mislead you. And this word exhorts you all to give heed to what is spoken; for it is not a history of things gone by, but a prophecy of things future, and which will surely come.
Not that we prophesy, for we are unworthy; but that the things which are written will be set before you, and the signs declared. Observe thou, which of them have already come to pass, and which yet remain; and make yourself safe.
Source: Catechetical Lectures (New Advent)