I have been searching about how machine can generate text by itself, this is the very basic question.

I have used openNLP which and detect name, detect grammar from the sentence and Markov Chains to Generate Text but shelley is just opposite of it.. can generate text of emotions.

Then in this question one said that

https://stackoverflow.com/questions/47902402/how-machine-generate-speech-text-by-itself/47903827#47903827

That’s because nobody knows

then i got a website shelley.ai crosses the limit of text generation and construct a horror stories.

Shelley is an AI program that generates the horror stories

now my question is how a machine generate text and also you have answer then please let me know how shelley would be working?