Professor Lénárt, István is the inventor of the spheres from Eötvös Loránd University in Budapest, Hungary. His passion is infectious. He talks about learning mathematics for everyone. I shared an office with him, spoke to him on multiple occasions, attended one of his workshops and attended one of his university classes where he was teaching future kindergarten teachers how to integrate geometry into the classroom (this was in Hungarian).
I watched him demonstrate how to do geometry constructions using the sphere. I watched him ask questions and make sure that everyone in the class could answer with confidence. I watched him discuss formally abstract concepts of geometry using a simple sphere and questioning. Every interaction with my new colleague István (Steven) was both intellectually and emotionally enjoyable. He knows that students can do mathematics and he expects them to learn.
When I am discouraged and wonder why I believe in mathematics for all, I will remember my interactions with István.