Melvyn Bragg and his guests discuss Strabo's Geographica. Written almost exactly two thousand years ago by a Greek scholar living in Rome, the Geographica is an ambitious attempt to describe the entire world known to the Romans and Greeks at that time. Strabo seems to have based his book on accounts of distant lands given to him by contemporary travellers and imperial administrators, and on earlier works of scholarship by other Greek writers. One of the earliest systematic works of geography, Strabo's book offers a revealing insight into the state of ancient scholarship, and remained influential for many centuries after the author's death.

With:

Paul Cartledge

Maria Pretzler

Benet Salway

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the science of matter and the states in which it can exist. Most people are familiar with the idea that a substance like water can exist in solid, liquid and gaseous forms. But as much as 99% of the matter in the universe is now believed to exist in a fourth state, plasma. Today scientists recognise a number of other exotic states or phases, such as glasses, gels and liquid crystals - many of them with useful properties that can be exploited.

With:

Andrea Sella

Athene Donald

Justin Wark

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss Max Weber's book the Protestant Ethic and the Spirit of Capitalism. Published in 1905, Weber's essay proposed that Protestantism had been a significant factor in the emergence of capitalism, making an explicit connection between religious ideas and economic systems. Weber suggested that Calvinism, with its emphasis on personal asceticism and the merits of hard work, had created an ethic which had enabled the success of capitalism in Protestant countries. Weber's essay has come in for some criticism since he published the work, but is still seen as one of the seminal texts of twentieth-century sociology.

With:

Peter Ghosh

Sam Whimster

Linda Woodhead

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the work of George Berkeley, an Anglican bishop who was one of the most important philosophers of the eighteenth century. Bishop Berkeley believed that objects only truly exist in the mind of somebody who perceives them - an idea he called immaterialism. His interests and writing ranged widely, from the science of optics to religion and the medicinal benefits of tar water. His work on the nature of perception was a spur to many later thinkers, including David Hume and Immanuel Kant. The clarity of Berkeley's writing, and his ability to pose a profound problem in an easily understood form, has made him one of the most admired early modern thinkers.

With:

Peter Millican

Tom Stoneham

Michela Massimi

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the Trinity. The idea that God is a single entity, but one known in three distinct forms - Father, Son and Holy Spirit - has been a central belief for most Christians since the earliest years of the religion. The doctrine was often controversial in the early years of the Church, until clarified by the Council of Nicaea in the late 4th century. Later thinkers including St Augustine and Thomas Aquinas recognised that this religious mystery posed profound theological questions, such as whether the three persons of the Trinity always acted together, and whether they were of equal status. The Trinity's influence on Christian thought and practice is considerable, although it is interpreted in different ways by different Christian traditions.

With:

Janet Soskice

Martin Palmer

The Reverend Graham Ward

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the life of Spartacus, the gladiator who led a major slave rebellion against the Roman Republic in the 1st century BC. He was an accomplished military leader, and the campaign he led contributed significantly to the instability of the Roman state in this period. Spartacus was celebrated by some ancient historians and reviled by others, and became a hero to revolutionaries in 19th-century Europe. Modern perceptions of his character have been influenced by Stanley Kubrick's 1960 film - but ancient sources give a rather more complex picture of Spartacus and the aims of his rebellion.

With:

Mary Beard

Maria Wyke

Theresa Urbainczyk

Producer: Victoria Brignell.

Melvyn Bragg and his guests discuss the eye. Humans have been attempting to understand the workings and significance of the organ for at least 2500 years. Some ancient philosophers believed that the eye enabled creatures to see by emitting its own light. The function and structures of the eye became an area of particular interest to doctors in the Islamic Golden Age. In Renaissance Europe the work of thinkers including Kepler and Descartes revolutionised thinking about how the organ worked, but it took several hundred years for the eye to be thoroughly understood. Eyes have long attracted more than purely scientific interest, known even today as the 'windows on the soul'.

With:

Patricia Fara

William Ayliffe

Robert Iliffe

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss Social Darwinism. After the publication of Charles Darwin's masterpiece On the Origin of Species in 1859, some thinkers argued that Darwin's ideas about evolution could also be applied to human society. One thinker particularly associated with this movement was Darwin's near-contemporary Herbert Spencer, who coined the phrase 'survival of the fittest'. He argued that competition among humans was beneficial, because it ensured that only the healthiest and most intelligent individuals would succeed. Social Darwinism remained influential for several generations, although its association with eugenics and later adoption as an ideological position by Fascist regimes ensured its eventual downfall from intellectual respectability.

With:

Adam Kuper

Gregory Radick

Charlotte Sleigh

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss chivalry, the moral code observed by knights of the Middle Ages. Chivalry originated in the military practices of aristocratic French and German soldiers, but developed into an elaborate system governing many different aspects of knightly behaviour. It influenced the conduct of medieval military campaigns and also had important religious and literary dimensions. It gave rise to the phenomenon of courtly love, the subject of much romance literature, as well as to the practice of heraldry. The remnants of the chivalric tradition linger in European culture even today.

Miri Rubin

Matthew Strickland

Laura Ashe

Producer: Thomas Morris.

Melvyn Bragg and his guests discuss the Phoenicians. The Greek historian Herodotus wrote about a people from the Levant who were accomplished sailors and traders, and who taught the Greeks their alphabet. He called them the Phoenicians, the Greek word for purple, although it is not known what they called themselves. By about 700 BC they were trading all over the Mediterranean, taking Egyptian and Syrian goods as far as Spain and North Africa. Although they were hugely influential in the ancient world, they left few records of their own; some contemporary scholars believe that the Phoenicians were never a unified civilisation but a loose association of neighbouring city-states.

With:

Mark Woolmer

Josephine Quinn

Cyprian Broodbank

Producer: Thomas Morris.