prayogaḥ ye ye 'rthakriyāsamarthās te vartamānāḥ, yathāvivādāspadībhūtā vartamānāḥ, arthakriyāsamarthāścātītādaya iti svabhāvahetuprasaṅgaḥ
The formulation is: Whatever things are capable of effective action are present, just as [those] present [things] whose [status] is not disputed, and past etc. things are capable of effective action - thus [this] is a reason based on essential nature.