Surya Siddhanta
सर्वत्रैव महीगोले स्वस्थानम् उपरि स्थितम् । मन्यन्ते खे यतो गोलस् तस्य क्वोर्धवम् क्व वाधः॥
As the shape of the earth is spherical (vartula), people in each place think themselves to be uppermost. But as the globe of earth is situated in ether, what then is its upper and lower side?
english translation