> The trouble is that I don't remember anything.

I read somewhere that our long-term memory has unlimited capacity, and there are basically three ways of measuring your memory:

- Recall: see whether you can recall the pertinent facts.

- Relearn: measure the time it takes for you to relearn the topic.

- Recognize: see if you can recognize key points in a previously learned topic when it's presented again to you.

Most people when they claim that they "don't remember anything" only refer to the recall-metric. But I bet that if you try to learn these ideas again, it'd take you much lesser time that it'd for a complete newbie => you haven't really lost everything you learned. It's just dormant.