Seventy-eight cards is a lot to "memorise" - I haven't even memorised the Periodic Table of Elements yet, or the seven-times-table, and I've had Tarot decks around me since some time in the late 1970s.
If you feel you have to memorise them, you're simply fashioning a rod to beat your own back with. You're just looking to damage your own self-esteem. Love them instead. Shuffle them a lot. Look at them a lot. Imagine. What's happening in that scene? What happened before, and what will happen a bit after? What is happening just beyond the edges of the image?
You'll learn a lot faster just spending time with your deck and thinking about it than you ever will, memorising. Go to the LWB if you really draw a blank on an image, or once you've worked out how it feels for you, to see if it gives you any extra ideas, but don't memorise. Think about one card, then think about an other. You'll get used to experiencing each card as you see it, that way.