What are some grandiloquent, or simply better, ways of expressing "an idea/thought suddenly came to me", or "an idea/thought struck me", or "I was struck by an idea/thought"?
An "Aha!" moment.
Or, "I had a sudden insight."
Or, "It finally dawned on me!"
Or, "I experienced a paradigm shift."
Or, "Suddenly, all the pieces fit together in one moment of inspiration!"
Or, "A revelatory moment."
Or, "An intuitive perception."
Or, "A mental breakthrough."
Or, "A eureka moment."
If you are writing primarily for everyday communication (e.g. email or chat), then always find the simplest language, while still being professional. In this case, you can simply say something like:
It just hit me, ...
It just struck me, ...
If you are writing longer form and want to be more expressive/stylistic, many of the answers above are great.
An idea just popped into my head. From Cambridge Dictionaries:
Something that pops into your head/mind is an idea that you suddenly have
(He jotted down story ideas that popped into his head.)
2 [USUALLY IN SINGULAR] informal A sudden clever idea: then he had a brainwave
More example sentences
I was fingering my car keys, wondering if my perverse appetite would last all the way to Tesco's and back, when I had a sudden brainwave.
Anyway, as she went on and got more and more into it, I had a sudden brainwave.
Those words hit Rick like stones, a brainwave and an idea quickly ensued.
A light bulb moment
Informal a moment of sudden inspiration, revelation, or recognition
[from the cartoon image of a light bulb lighting up above a character's head when he or she has an idea]
Related to the concept of light providing an answer, is the noun
illumination "In a moment of illumination" TFD
- spiritual or intellectual enlightenment; insight or understanding