As a writer Seneca is known for his philosophical works, and for his plays, which are all tragedies. His prose works include a dozen essays and one hundred twenty-four letters dealing with moral issues. These writings constitute one of the most important bodies of primary material for ancient Stoicism. As a tragedian, he is best known for plays such as his "Medea", "Thyestes", and "Phaedra". Seneca's influence on later generations is immense—during the Renaissance he was "a sage admired and venerated as an oracle of moral, even of Christian edification; a master of literary style and a model dramatic art."