Ven. Buddhaghosa himself has said in his book THE PATH OF PURIFICATION (VISUDDHIMAGGA) that 'one's own opinion is the weakest authority of all and should only be accepted if it accords with the Suttas' (DA. 567-68). So far I have not come across such an explanation in the Suttas. So until I come across such an explanation in the Scriptures (Sutta-Vinaya), I’ll have to take it that Ven. Buddhaghosa’s own opinion is the weakest authority of all and should only be accepted if it accords with the Suttas'.
To understand the Four Noble Truths the 4 'foundations of mindfulness’ is there. The Satipatthāna is there for this purpose. The realization one gets out of it is the understanding of Paticca Samuppāda (dependent origination or the universal law of cause and effect). That is, the ability of seeing things in life according to cause and effect.
The first step toward the Noble Eightfold Path is for one to become faith-devoted – that all the answers are there in the Suttas. One who accepts this path of Dhamma admits that there is suffering of this Samsara. He accepts there exists a cause and effect. He accepts the fact that one needs to be free from suffering. He also accepts that the Supreme Buddha has freed Himself from suffering and the Dhamma can free us from that suffering. He accepts that the disciples (of the Buddha) will have to follow the Dhamma and that there are disciples who have attained the Arahantship by practicing the Dhamma.
In one who comes to these notions, an internal spiritual faculty will be formed. It is a faculty that operates within the mind. This person will come to the Noble Eightfold Path, as this person has accepted the Supreme Buddha, His Dhamma, and His disciple monks wholeheartedly. It is this person who will begin to study the scriptures in earnest. Only then he/she will begin to realize the Paticca Samuppāda gradually.