20. It is by assuming as a fact that the southern extremity of India is under the same parallel as Meroe, a thing affirmed and believed by most writers, that we shall be best able to show the absurdities of the system of Hipparchus. In the first book of his Commentaries he does not object to this hypothesis, but in the second book he no longer admits it; we must examine his reasons for this. He says, “when two countries are situated under the same parallel, but separated by a great distance, you cannot be certain that they are exactly under the same parallel, unless the _climata_[543] of both the places are found to be similar. Now Philo, in his account of a voyage by sea to Ethiopia, has given us the _clima_ of Meroe. He says that at that place the sun is vertical forty-five days before the summer solstice,[544] he also informs us of the proportion of shadow thrown by the gnomon both at the equinoxes and solstices. Eratosthenes agrees almost exactly with Philo. But not a single writer, not even Eratosthenes, has informed us of the _clima_ of India; but if it is the case, as many are inclined to believe on the authority of Nearchus,[545] that the two Bears are seen to set in that country, then certainly Meroe and the southern extremity of India cannot be under the same parallel.”[546] [Such is the reasoning of Hipparchus, but we reply,] If Eratosthenes confirms the statement of those authors who tell us that in India the two Bears are observed to set, how can it be said that not a single person, not even Eratosthenes, has informed us of any thing concerning the _clima_ of India? This is itself information on that point. If, however, he has not confirmed this statement, let him be exonerated from the error. Certain it is he never did confirm the statement. Only when Deimachus affirmed that there was no place in India from which the two Bears might be seen to set, or the shadows fall both ways, as Megasthenes had asserted, Eratosthenes thereupon taxed him with ignorance, regarding as absolutely false this two-fold assertion, one half of which, namely, that concerning the shadows not falling both ways, Hipparchus himself acknowledged to be false; for if the southern extremity of India were not under the same parallel as Meroe, still Hipparchus appears to have considered it south of Syene.