They include:
1- Senses
The five senses (vision, hearing, touch, smell, and taste) are the first means given by God to human beings to know the world. With the help of them, human beings recognize the things and affairs around them. They hear what can be heard, smell scents, see what can be seen, taste what can be tasted and touch things.
God says in Verse 78 of Surah An-Nahl: “Allah has brought you forth from your mothers' wombs when you knew nothing, and then gave you hearing, and sight and thinking hearts…”
2- Intellect
The intellect is a great divine blessing for human beings. God has blessed mankind with this precious gift so that he can use it to both know what can be sensed and have the power of analyzing and exploring.
3- Vahy (Revelation)
Revelation is the source of many teachings and much knowledge. Since revelation originates from God’s unlimited knowledge, it gives humanity the most pure and reliable cognizance. Through revelation, humanity has achieved invaluable knowledge about the universe and its origin, creation, the past and future of the world and spiritual issues that could not have been achieved through any other way.
Sources of Cognizance
God has urged us to study, reflect on and try to know more about a number of issues;
1- Nature
Many verses of the Quran call on us to reflect on different natural phenomena like creation of heavens and earth, succession of day and night, mountains, animals, etc.
2- History
Studying history and learning about previous people’s ups and downs and victories and defeats are very informative and instructive, giving one knowledge and cognizance. By studying history, one can recognize many of the secrets, traditions and laws of the world.
The Quran considers the story of the people living before us as a lesson: “Certainly in the stories of the bygone people there is a lesson for people of understanding.” (Verse 111 of Surah Yusuf)
God, in verse 176 of Surah Al-A’raf calls on the Holy Prophet (PBUH) to narrate the stories of the past people: “… recount to them these narratives, in order that they reflect.”
3- Human
Studying human and different aspects of his capabilities, talents, needs, etc enhances and deepens one’s knowledge. God says in Verse 53 of Surah Al-Fussilat: “We will show them our signs in all the horizons and in themselves, until it is clear to them that it is the truth.”
Imam Ali (AS) said: “"You think you are a small entity, but within you is enfolded the entire Universe.”