Agarwood only exists because the tree gets sick. When Aquilaria heartwood is infected, it floods the wound with resin, and that resin is what is distilled. Uninfected wood gives nothing, which is why agarwood is one of the most expensive materials on earth. Agarospirol, jinkoh-eremol and chromone compounds give the deep, sweet, balsamic smell. Those profiles differ markedly between the four main Aquilaria species, which is why origin changes the character so much.^[1]