Manisha Panchakam is a stotra containing five verses composed by Shri Adi Shankaracharya. It is said that in these five verses Shri Adi Shankaracharya brings out the essence of Advaita Vedanta. The word Manisha means firm conviction, and Panchak means five. So the name of the stotra can be translated as “Five verses of firm conviction“. 

One day Shri Adi Shankaracharya was on his way to Lord Vishwanatha temple, he saw an outcast walking towards him. Shri Shankara asked that man to move away. The man humbly asked him questions which become the form of 2 verses as below :

अन्नमायादन्नमयमथवा चैतन्यमेव चैतन्यात्
यतिवर दूरीकर्तुं वाञ्छसि किं ब्रूहि गच्छगच्छेति ॥ १ ॥

Do you want the body made up of food to move away from another body made up of food? Or do you want consciousness to move away from consciousness? O great among the twice-born! What is it that you want to move away by saying, “move away, move away”?

प्रत्यग्वस्तुनि निस्तरङ्गसहजानन्दावबोधाम्बुधौ
विप्रोऽयं श्वपचोऽयमित्यपि महान्कोऽयं विभेदभ्रमः ।
किं गङ्गाम्बुनि बिम्बितेऽम्बरमणौ चाण्डालवीथीपयः
पूरे वाऽन्तरमस्ति काञ्चनघटीमृत्कुम्भयोर्वाऽम्बरे ॥ २ ॥

In the ripple-less (changeless), naturally blissful ocean of the Self, how can there be an illusion of difference in the form, “This is a Brahmana and this is an outcaste”. Is there any difference between the reflection of the sun in the waters of the Ganga and its reflection in the water in the streets of the outcastes? Or is there any difference when the water containers is golden vessels and earthen pot?

Shri Adi Shankaracharya immediately realizes that the man is none other than Lord Shankara and he answers to His questions in below 5 verses which is known as  “Manisha Panchakam” 

जाग्रत्स्वप्नसुषुप्तिषु स्फुटतरा या संविदुज्जृम्भते
या ब्रह्मादिपिपीलिकान्ततनुषु प्रोता जगत्साक्षिणी
सैवाहं न च दृश्यवस्त्विति दृढप्रज्ञापि यस्यास्ति
च्चण्डालोऽस्तु स तु द्विजोऽस्तु गुरुरित्येषा मनीषा मम॥ १ ॥

If a person has attained the firm knowledge that he is not an object of perception, but is that pure consciousness which shines clearly in the states of waking, dream and deep sleep, and which, as the witness of the whole universe, dwells in all bodies from that of the Creator Brahma to that of the ant, then he is my Guru, irrespective of whether he is an outcaste or a Brahmana. This is my firm conviction.

ब्रह्मैवाहमिदं जगच्च सकलं चिन्मात्रविस्तारितं
सर्वं चैतदविद्यया त्रिगुणयाऽशेषं मया कल्पितम् ।
इत्थं यस्य दृढा मतिस्सुखतरे नित्ये परे निर्मले
चण्डालोऽस्तु स तु द्विजोऽस्तु गुरुरित्येषा मनीषा मम ॥ २ ॥

I am pure Consciousness, and this entire universe, is only an expansion of pure Consciousness. Out of this Maya all this that we see, made of the three gunas, has been conjured by imagination. He whose intellect is firmly established in the all blissful, eternal, Supreme Reality, be he a Chandala or be he a Brahmana, such a one is indeed worthy of being a Guru. This is my firm conviction.

शश्वन्नश्वरमेव विश्वमखिलं निश्चित्य वाचा गुरो-
र्नित्यं ब्रह्म निरन्तरं विमृशता निर्व्याजशान्तात्मना
भूतं भावि च दुष्कृतं प्रदहता संविन्मये पावके
प्रारब्धाय समर्पितं स्ववपुरित्येषा मनीषा मम ॥ ३ ॥

He who have come to the definite conclusion, under the instruction of his Guru, that the entire universe is always perishable, he who, with a calm and pure mind constantly meditates on Brahman, and who has burnt his past and future sins in the fire of knowledge, offers his body to  Prarabdha. Such a one is worthy to be a Guru,  this is my firm conviction.

या तिर्यङ्नरदेवताभिरहमित्यन्तः स्फुटा गृह्यते
यद्भासा हृदयाक्षदेहविषया भान्ति स्वतोऽचेतनाः
तां भास्यैः पिहितार्कमण्डलनिभां स्फूर्तिं सदा भावय-
न्योगी निर्वृतमानसो हि गुरुरित्येषा मनीषा मम ॥ ४ ॥

The knowledge by which all life forms – animals, human-beings and the gods – project the ‘I’ consciousness, by which the mind, the organs of perceptions and such otherwise insentient bodies appear to become alive, and which is the source of light yet being eclipsed by the very mind that is lit due to its presence, that is the supreme knowledge and whoever has
the steadfast contemplation and complete gratification on this wisdom is the preceptor. This is my firm conviction.. 

यत्सौख्याम्बुधिलेशलेशत इमे शक्रादयो निर्वृता
यच्चित्ते नितरां प्रशान्तकलने लब्ध्वा मुनिर्निर्वृतः ।
यस्मिन्नित्यसुखाम्बुधौ गलितधीर्ब्रह्मैव न ब्रह्मविद्
यः कश्चित्स सुरेन्द्रवन्दितपदो नूनं मनीषा मम ॥ ५ ||

By realizing, only a few droplets of the ocean of the absolute-bliss, Indra and other gods are enjoying immense pleasures in their worlds. In this world too, so are the Sages(Muni) of clear intellect who are immersed in much greater bliss only within their serenely focused mind. Through unwavering commitment, when the Sage ultimately and completely merges in the Self, the ocean of Absolute-Bliss, he is no more the knower of Brahman, but the Brahman himself. Such a person, whoever he may be, is one whose feet are fit to be worshipped by Indra himself. This is my firm conviction.

Source : I am immensely grateful to read the Manisha Panchakam and understand its meaning from below sources by the authors. Thank you.
-https://sanskritdocuments.org/sites/snsastri/Manishapanchakam.pdf
-https://www.bhagavatadharma.co.uk/docs/Manisha_Panchakam22.pdf
-Wikipedia