An easier way is to use n-grams. You can download 3 and 4 word n-grams from google here: http://ngrams.googlelabs.com/datasets
There are roughly 32 billion of google 4-grams.
There are roughly 32 billion of google 4-grams.
Summing up, a meaningful 4-word phrase, is, in the terminology of the article, "risky".
My advice: use generated passwords, and apps like 1password to remember them.