http://lagrange.math.siu.edu/
3 + 4 = 7
The oldest spiritual equation
https://plato.stanford.edu/
Keith Hankins, Peter Vanderschraaf
Stanford Encyclopedia of Philosophy, Game Theory and Ethics
https://www.diva-portal.org/
Helgard Mahrdt
Feminist Philosophy Time, history and the transformation of thought, Chapter 6 Hannah Arendt – To Think “Without Banisters”
https://www.earlymoderntexts.com/
René Descartes
The Passions of the Soul
https://www.britannica.com/
Ian Stewart
Pythagoreanism in Number symbolism
https://chs.harvard.edu/
Kalvesmaki, Joel
The Theology of Arithmetic: Number Symbolism in Platonism and Early Christianity
https://philosophy-science-humanities-controversies.com/
G.W.F. Hegel
Economics Dictionary of Arguments
https://medium.com/
Jin Wu
What it's Like to "Feel" Numbers — Inside the Brain of a Synesthete
https://www.museumofplay.org/
Scott G. Eberle
The Elements of Play Toward a Philosophy and a Definition of Play