President Rodrigo Duterte’s knowledge and understanding of the law seems to match his literary skills as he used a number of quotes from historical figures.

More than just quotes to add zest to an otherwise generic presidential speech, Duterte’s allusions also seems to highlight his character as a politician and as an ordinary person.

READ: Inaugural address of President Duterte

See where Duterte appeared to have gotten the quotes he used in the inaugural speech.

1. From a National Artist

Duterte first quoted National Artist for Literature Francisco Sionil Jose: “We have become our own worst enemies and we must have the courage and will to change ourselves.”

The quote seems to come from Jose’s fiction novel “Ben Singkol,” whose titular character is an accidental hero but is actually a coward during the Japanese occupation of the Philippines.

Duterte seemed to have been paraphrased from this part in the novel: “You will find that our enemies are our own kin. It is they who betray us. So learn this most important lesson-in the end, our worst enemy is ourselves.”

Jose has expressed support for Duterte in the 2016 elections.

2. U.S. Presidents

Another personality mentioned by Duterte is former US president Franklin Roosevelt. In his speech, Duterte quoted Roosevelt as saying: “The test of government is not whether we add more to the abundance of those who have much. It is whether we provide to those who have little.”

Roosevelt’s exact quote is: “The test of our progress is not whether we add more to the abundance of those who have much; it is whether we provide enough for those who have too little.”

The quote comes with what Duterte determines as a need to eradicate corruption, which he said is a contributor to poverty. This is also in similar fashion to the person he quotes next, former US president Abraham Lincoln.

Duterte said he draws inspiration from Lincoln, quoting the anti-slavery president in his speech: “You cannot strengthen the weak by weakening the strong. You cannot help the poor by discouraging the rich. You cannot help the wage earner by pulling down the wage payer. You cannot further brotherhood by inciting class hatred among men.”

The quote however comes from the “Ten Cannots” written in 1916 by William J.H. Boetcker, an American Presbyterian minister.

A book by Edward Steers entitled “Lincoln Legends: Myths, Hoaxes, and Confabulations Associated with our Greatest President,” revealed that the said quote was a common erroneous reference to Lincoln. This was due to the use of a leaflet printed in the 1940s that erroneously switched the attribution from Boetcker to Lincoln.

Since then, many have thought that the “Ten Cannots” were from Lincoln, so Duterte’s was not the first misattribution.

In addition, Duterte only used half of the “Ten Cannots” in his speech. The rest are as follows: “You cannot establish sound security on borrowed money. You cannot keep out of trouble by spending more than you earn. You cannot build character and courage by destroying men's initiative and independence. And you cannot help men permanently by doing for them what they can and should do for themselves.”

3. A Roman statesman, apparently

The last quote that Duterte used in his inaugural speech – and one whose source is difficult to find: “I have no friends to serve, I have no enemies to harm.”

This part of his speech stressed that Duterte has no personal interests to protect other than those of the Filipino people, and one that he said has been his “article of faith.”

But the quote doesn’t seem to appear anywhere. However, it is closer in meaning to an epitaph of Lucius Cornelius Sulla Felix, a general from ancient Rome.

Sulla’s epitaph reads: “No friend ever served me, and no enemy ever wronged me, whom I have not repaid in full.”

This particular quote seems to be a favorite of Duterte as he had already used it in a previous speech, particularly the Senate hearing on rice smuggling in 2014 when he described his norm of conduct as a public servant.