The thesis focuses upon research of the philosophical component of two writings by the Croatian Renaissance thinker Benedikt Kotruljević (c. 1416–1469). He completed his first writing in 1458 and entitled it, according to the most recent research results, Libro del arte dela mercatura. In its four books he considered the art of trade. This writing received its reception from two of the most prominent Croatian Renaissance philosophers: Franciscus Patricius and Nicolò Vito di Gozze. Since he recognized the value of its contents, Patricius edited and published the first printed edition of the writing on the art of trade in 1573. In his most significant work on political philosophy Dello stato delle Republiche (On the Structure of States) published in 1591, Nicolò Vito di Gozze recommended Kotruljević’s writing on the art of trade stating that it is “most useful to every researcher of this trade” and that it will teach them “how to trade justly and thereto very successfully.” Kotruljević completed his second writing, which is commonly known as De navigatione, in 1464. In its first three completed books, as well as in its fourth uncompleted book, he exposed his thoughts on navigation. The delayed reception of De navigatione must be attributed to the fact that the handwritten version of its transcript was first found as late as 1995. The philosophical component in the writing on the art of trade manifests itself in three ways. In it, Kotruljević proved himself to be a connoisseur of the history of philosophy. Apart from the information offered by previous research that he relied on more than twenty philosophers and philosophical sources in it, the thesis provides information that he also relied on the thoughts of the following fourteen philosophical thinkers: Callisthenes of Olynthus, Zeno of Citium, Marcus Terentius Varro, Valerius Maximus, Pliny the Elder, Pliny the Younger, Gaius Julius Solinus, Basil the Great, John Chrysostom, Isidore of Seville, Dante Alighieri, Francesco Petrarca, Giovanni Boccaccio, and Antonino Pierozzi or Antoninus of Florence. Therefore, in his writing on the art of trade Kotruljević referred to the philosophical thought of as many as forty thinkers from antiquity to his day. Secondly, all of the four books of the writing on the art of trade contain an ethical component. For instance, in the first book he constituted the art of trade on justly (iustamente) arranged business. He also claimed that God gave humans free will (libero arbitrio), egregious mind (ingiegno egregio) and prudence (prudentia) in order for them to be able to resist the influence of higher celestial bodies. This proves that Kotruljević deemed human beings capable of self-determination (homo secundus Deus / Deus in terris). In the second book, he pointed out the importance of merchant’s faith from an ethical perspective. Merchants should practice religion to renounce their vices, and they should nurture the virtue of wisdom (sapiencia) at the same time. Kotruljević built the perfect merchant who is supposed to obtain numerous ethical virtues in the third book. In his opinion, three of these virtues were of utmost importance for merchants: prudence (prudentia) which is a common virtue (comune virtu), justice (justitia) which is a virtue that incorporates many other virtues (questa virtu incorpora multe altre), and temperance (temperantia) which is the highest virtue (summa virtu). The contents of the third book also prove that Kotruljević advocated the Renaissance ideal of the universally educated man (homo universalis). In the fourth book, he founded merchant’s economic life (la vita yconomica) on both ethical and political grounds. For instance, the merchant should govern his household and family (governo dela casa et dela famiglia) same as a king who rules over his subjects, and in so doing he should be very prudent (havere multa prudencia), venerable (venerabile), and honest (honesto). In the first, third and the fourth book of his writing on the art of trade, Kotruljević also considered issues belonging to philosophy of education. In the first book he believed that it was necessary for children to nurture their souls, spirits and bodies at the same time. Kotruljević also named three prerequisites for children to become perfect merchants: 1) they should be sons of a merchant, since they will possess intrinsic virtues (virtu intrinseche) similar to their fathers; 2) they should get acquainted with the rules of trade from a very young age and should absorb the movements, customs and conversations of merchants; 3) they should be persistent in doing their job. In the third book, he stated that the key to the progress of mankind lies in education. Young merchants should excel and surpass their parents in acquiring virtues (excellere et passarli in qualche virtu), and they should learn grammar, rhetoric, dialectic, philosophy, astrology, theology and law. Kotruljević accentuated the crucial influence of parents in the educational process in the fourth book. Parents must offer their children education (educare), nutrition (nutrire), and they need to teach them good customs (costumare), whereas children owe their parents obedience (obediencia). The philosophical component of Kotruljević’s writing on navigation also reflects itself in three ways. In the first chapter of the first book, Kotruljević once again proved to be a connoisseur of the history of philosophy, showing that he had knowledge on both ancient Greek (Thales of Miletus, Anaximander, Anaximenes of Miletus, Anaxagoras, Diogenes of Apollonia, Archelaus, Socrates, Plato, Aristotle) and medieval philosophers (Augustine of Hippo, Rabanus Maurus, Peter Lombard, Albert the Great). The issues belonging to philosophy of nature are present in the first and the third book of the writing on navigation. For instance, in the first book he mainly focused on water as one of the four elements. But he also tried to reconcile Christian Neo-Platonic worldview, led by Augustine, with the thought of pagan philosophers and astronomers, led by Aristotle and Ptolemy, which shows that his writing on navigation contains another characteristic of Renaissance philosophy: syncretism. In the third book, Kotruljević considered the following meteorological phenomena: winds, rainbows, halos, lightning and, as he called them, fires descending from the air. He wrote the most about winds, mainly on what causes them, what are their characteristics and what is their role in navigation, since he thought they were the most important part of navigation (la potisima parte ne la navigatione). Kotruljević also pondered upon astronomical and astrological issues, namely upon twelve zodiac signs, two ephemerides, properties of the seven known planets, solstices and equinoxes, and time measurement. He paid the most attention to the twelve zodiac signs, considering that type of knowledge useful to sailors for two reasons: 1) each of the zodiac signs brings different weather; 2) zodiac signs affect human inclinations and actions. The second and the third book of De navigatione contain an ethical component. Kotruljević presented ethical virtues necessary for the four members of the chain of command on ships in the second book. For example, the captain of a ship should be temperate (temperato) and he should not be avaricious (non avaro). In the third book, Kotruljević focused on the influence of celestial bodies on human ethical actions. He was convinced that, for instance, people born in Aquarius will be wise (savio) and evil (malo), and that Jupiter’s influence makes people capable of ruling and that they become temperate (temperati).