Discuss and recommend old textbook alternatives to modern textbooks, compare and criticize modern texts with their older counterparts, appreciate the eloquence found in older textbooks and realize this will never be the case for modern texts.

>Sites for finding older textbooks
https://mirtitles.org/
English translations of Soviet texts

https://www.forgottenbooks.com/en/Mathematics
Largest collection of antiquated texts among the sites mentioned. Some texts are very old and obscure.

http://www.survivorlibrary.com/8-category/172-library-mathematics.html
Mostly 19th and 20th century American texts used for secondary and introductory college Mathematics

https://onlinebooks.library.upenn.edu/
A relatively small collection of texts used in introductory college Mathematics

https://archive.org/

>Please keep the discussion to Mathematics and the physical sciences only
The main focus of this thread is older textbooks relating to Mathematics. Texts for the physical sciences are allowed as well, but try not to recommend anything that is too antiquated and mentions concepts which have been disproved. Or if you do mention them, make sure to state that this is the case.