“If I understand correctly, an impure mind has a more difficult time grasping concepts and concentrating during meditation.”
That is correct, upekkha.
– There are many people who try to read deep suttas and get to Nibbana. But they have defiled minds, like most average humans. So, their efforts mostly go to waste.
I think you are making the right decision to start at the beginning. You will definitely see the truth of your above statement if you give enough time.
Initially, it may take some time. So, you need to give your best without thinking about the results day-to-day. Don’t be discouraged if you don’t notice any improvements over the first few weeks.
– The Buddha gave the following analogy. A farmer does not look for the results of his efforts each day. He plants the crops and takes care of them. With proper care, he WILL get the rewards for his labor in due time.
From another perspective, it is like pushing a stalled car. It is hard to get it to move first. But once it starts moving, it becomes much easier.
I hope you will report your progress, even if you are not making much progress initially. You may get suggestions from others too.