What is the secret ballot in Pericles, why was it secret?

The principle of secret ballot means that no one except the voter (referendum participant) has the right to know about the content of his personal expression of will and no one has the right to exert pressure on the will of the voter (referendum participant). In international law, this principle is enshrined in article 21 of the Universal Declaration of Human Rights; paragraph 7.4 of the Document of the Copenhagen Meeting of the Conference on the Human Dimension of the Conference on Security and Cooperation in Europe (CSCE, currently the Organization for Security and Cooperation in Europe – OSCE, whose member states are 56 states); Article 5 of the Convention on the Standards of Democratic Elections, Electoral Rights and Freedoms in the Member States of the Commonwealth of Independent States.