When one has mastered the 'Elementary Teachings' [the milk of the word of God], the person is ripe to eat solid food [the mature teachings]. Of course solid food includes meat and some meats are strong to chew. 'Strong Meat' is strong but quite delicious. It is full of hope and prophetic insight. For the spiritual mind it is an invaluable asset, an appreciable truth that must be meditated upon over and over again; a never exhaustible meal.