Why is dattatreya called a guru of entire universe?

Ramana Maharishi says:  "Dattatreya is the universal Guru, isn’t he? And he has said that the whole world was his Guru. If you look at evil you feel you should not do it. So he said evil also was his Guru. If you see good, you would wish to do it; so he said that good also was his Guru; both good and evil, he said, were his Gurus. It seems that he asked a hunter which way he should go, but the latter ignored his question, as he was intent upon his aim to shoot a bird above. Dattatreya saluted him, saying, ‘You are my Guru! Though killing the bird is bad, keeping your aim so steadfast in shooting the arrow as to ignore my query is good, thereby teaching me that I should keep my mind steadfast and fixed on Ishwara. You are therefore my Guru.’ In the same way he looked upon everything as his Guru, till in the end he said that his physical body itself was a Guru, as its consciousness does not exist during sleep and the body that does not exist should therefore not be confused with the soul — dehatmabhavana (the feeling that the body is the soul). Therefore that too was a Guru for him. While he looked upon the whole world as his Guru, the whole world worshipped him as its Guru."

Manamantha

Manamanta oka andamaina prapancham ela vuntundo choopinchina chakkati chithram. Eppudu patha chithralani choosi ilaanti chitralu ippudenduku raavu ani badha padevaariki oka aanimuthyam.. konni chithralu choodagane marchipotham.. konni chithralu aanandistham.. konni chithralanu choosaka, idi chithram ante ani oka adbhuthamaina anubhoothiki lonavutham.. manamantha alanti anubhoothini panche chithram. mana gadilo daachukune pade pade choodavalasina chithram idi ante athisayokthi kaadu.. ilanti chithram telugulo raavatam adi kooda telugu vallu thiyyatam manam nijamga garvinchadagga vishayam..
Telugu chithrallo kathanayakudu, kathanayika, 6 paatalu konchem haasyam thappa inkem vundavu ani anukune vaariki ee chithram choosthe noti nunchi maata radu.. Indulo prathi pathra therapaina mana jeevithanni prathibimbinchela cheyyatam darsakudi prathibhaki nidarshanam.. nannu adigithe ee chithram pillalaki, yuvathaki appudappudu choopinchi manchi vaallu cheddaga maarataniki kaaranamento kallaku kattinattu choopinchi vaallani manchi maargam lo nadichela cheyyaali..
Andari jeevithamlo balyam, yavvanam, gruhasthu jeevitham vuntayi.. balyamlo vunnappudu vallallo amayakathvam ela vuntundo.. sneham ela vuntundo .. aa papatho vunna sanniveshalu anni inta andamga vuntunda prapancham ani anipinchela cheyyaka maanadu.. papa snehithudu thappipothe athadini vethakadaniki pattu vadalakunda chese prayathnalanni saphalam avvalani maname korukuntam. antaga leenamavutham aa paathratho.. oka madhya tharagathi amma sarukulalo evi thakkuvaku vasthunnayo ani dooram prayaninchi kashtapaduthunte.. aa amma paina vungaram kottesindemo ani konni kshanalu bangaru angadi vaadu anumanisthunte.. prathi okkariki thana thalli gurthu raaka maanadu.. oka madhya tharagathi thandri pillala kosam konchem addadarlu thokki okanoka samayam cheyyakoodani pani chesi ayyo thappu chesane ani badha paduthuntunte .. mana jeevithamloni chala ghatanalu gurthu raka manavu.. oka yuvakudu eppudu chaduvulo mundunde vaadu, thoti vaariki thana gnananni panchevaadu oka ammayi premalo padi jeevithanni nashanam chesukuntunte ayyo evaraina vachi athanni kaapadithe bavundu ani anipinchaka maanadu..
Inta chakkani chithram dabbulu sampadinchinda leda ani anekante.. manasuni gelichinadi ani cheppali.. mana manasulani gelichi chala kalam paatu nilichipoyela chesthundi ... manam enno vandala chithralanu choosthuntam.. kaani avi choodaka poyina vache nashtam ledu.. kaani ee chithram choosthe inka vanda chithralu kooda choodavalasina avasaram ledu..
Intati manchi chithranni aavishkarinchina prathi okkariki hrudaya poorvaka vandanamulu..