>>5036
>In IIH Bardon makes it very clear that at the beginning you're going to be working entirely in the imagination; vivid perception indistinguishable from the physical is just the sign that you've mastered the exercise.
Yes, but those are extremes of imagination, the feats described are extreme relative to what we all normally experience, and that's why you are easily able to gauge your progress. Just like the first difficult mental exercise (Dharana) where you have to concentrate on a single thought for 10 minutes without any mental interruptions.

Even in the steps before you start actually doing magic, the feats you have to achieve seem pretty much impossible and are measurable.

>IIH is a good regimen but if you go into it with the mentality that you're just going to ignore purely astral phenomena and only treat physical phenomena as a 'success' you're going to be very frustrated.
It's not just about it being measured, but it must be an "extreme" if I have to gauge it based on personal experience.

For example, the following exercise:
Magic Psychic Training 3
>Imagine all around you, even the entire universe being fiery. Now inhale the fire element with your nose and, at the same time, with your whole body, (pore-breathing). Draw deep breaths regularly, without pressing air or straining the lungs. The material and the astral body ought to resemble to an empty vessel into which the element is being inhaled, better to say, sucked in, with each breath. The heat of the element has to be increased and pressed into the body with each breath. This heat ought to grow more and more intense, with every breath. The heat and the expansion power must become stronger, the fiery pressure higher and higher, until you feel yourself, at last, fiery, red-hot

I think if I'm doing an exercise like this it will be very clear if I'm doing it correctly or not. I will either feel an intense and increasing heat or not. It isn't vague at all even though I can't actually measure it externally.

That's as early as Step 3. The concentration exercises (Step 2) also allow you to gauge your progress, because if you can make yourself taste and hear things that aren't there, that's a pretty extreme and observable thing (even if you can't measure it).