Use simulation speed of 1s/s and change one of the Resistor values from 470k to 500k to start the oscillation (otherwise it will take 30s+), then you can switch it back to 470k. I have tried to give myself a step by step explanation here: https://www.tapatalk.com/groups/japanpeuf/oscillator-circuit-using-transistors-and-capacitor-t1313175.html
