In a career spanning four decades (1946-1985) he made important contributions to Philippine diplomacy and the Philippine foreign service.
First, he served with distinction (as reflected in awards received from the Philippine Government and host countries) as Philippine Ambassador in the Americas, Asia and Europe.
Second, he represented the Philippines in major international organizations, notably as Philippine Permanent Representative to the United Nations in New York in the early 1980s (his last posting as a diplomat) and earlier as Permanent Representative to UNESCO while posted in Paris.
Third, he implemented the opening of Philippine diplomatic relations with socialist countries in Central and Eastern Europe.
He was the first Filipino diplomat accredited as nonresident Ambassador to three of these countries, and subsequently became the first Philippine Ambassador to the Union of Soviet Socialist Republics.
Fourth, he had a lasting impact on the practice of Philippine diplomacy.
One reason was his commitment to service, reflected in his steadfast response to extreme or difficult circumstances, such as the attack on his residence in Saigon during the 1968 Tet Offensive.
After his death the media was filled with "eulogies celebrating his life and work, his principles and patriotism".
Another reason was his widely acknowledged expertise in the practice of diplomacy.
For example, his book, A Guide to Protocol (published in 1949 and 1959) was the main reference for Filipino diplomats seeking to build the Philippine foreign service in the period after WWII.
This book has continued to guide Philippine diplomatic practice decades after its publication.